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24.9.14 internet applications notes-miss sushma jaiswal

This document provides notes on Internet applications for students. It begins with an introduction by the author, Sushma Jaiswal, thanking readers and students. The notes then cover topics such as what is the Internet, the history and development of the Internet and World Wide Web, components of the Internet like browsers, URLs, domains and more. Examples, definitions and explanations are provided throughout in a self-explanatory "teach yourself" style.

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Internet Applications Notes Sushma Jaiswal Assistant Professor, CSIT Guru Ghasidas Vishwavidyalaya, Bilaspur (C.G.)
To all my loving students
Preface I am glad to present this notes, especially designed to serve the needs of the students of Bsc Vth semester Computer Science. The notes have been written keeping in mind the general weakness in understanding the fundamental concepts of the topics. The notes are self-explanatory and adopt the “Teach Yourself” style. It is also based on question-answer pattern. The language of notes is quite easy and understandable based on scientific approach. Thanks to the online readers for their overwhelming response to our previous notes of computer graphics, software engineering, software testing & programming based numerical methods. The feedback and the response we received, encouraged me to write to this notes. Any further improvement in the contents of the notes by making corrections, omission and inclusion is keen to be achieved based on suggestions from the readers for which the author shall be obliged. I acknowledge special thanks to all who involve directly and indirectly, which are the backbones and main concept provider and also have been constant source of motivation throughout this endeavour. They played an active role in coordinating the various stages of this endeavour and spearheaded the collecting work. I look forward to receiving valuable suggestions from professors of various educational institutions, other faculty members and my loving students for improvement of the quality of the notes. The reader may feel free to send in their comments and suggestions to the under mentioned address. Sushma Jaiswal Email-Id jaiswal1302@gmail.com
Internet BasicsInternet BasicsInternet BasicsInternet Basics What is the Internet?What is the Internet?What is the Internet?What is the Internet? Ans. The Internet, sometimes called simply "the Net," is a worldwide system of computer networks - a network of networks in which users at any one computer can, if they have permission, get information from any other computer (and sometimes talk directly to users at other computers). The U.S. Department of Defense laid the foundation of the Internet roughly 30 years ago with a network called ARPANET. But the general public didn't use the Internet much until after the development of the World Wide Web in the early 1990s. In 1957, the U.S. government formed the Advanced Research Projects Agency (ARPA), a segment of the Department of Defense charged with ensuring U.S. leadership in science and technology with military applications. In 1969, ARPA established ARPANET, the forerunner of the Internet. ARPANET was a network that connected major computers at the University of California at Los Angeles, the University of California at Santa Barbara, Stanford Research Institute, and the University of Utah. Within a couple of years, several other educational and research institutions joined the network. In response to the threat of nuclear attack, ARPANET was designed to allow continued communication if one or more sites were destroyed. Unlike today, when millions of people have access to the Internet from home, work, or their public library, ARPANET served only computer professionals, engineers, and scientists who knew their way around its complex workings.
What is the World Wide Web?What is the World Wide Web?What is the World Wide Web?What is the World Wide Web? Ans. The World Wide Web came into being in 1991, thanks to developer Tim Berners- Lee and others at the European Laboratory for Particle Physics, also known as Conseil European pour la Recherche Nucleure (CERN). The CERN team created the protocol based on hypertext that makes it possible to connect content on the Web with hyperlinks. Berners-Lee now directs the World Wide Web Consortium (W3C), a group of industry and university representatives that oversees the standards of Web technology. Early on, the Internet was limited to noncommercial uses because its backbone was provided largely by the National Science Foundation, the National Aeronautics and Space Administration, and the U.S. Department of Energy, and funding came from the government. But as independent networks began to spring up, users could access commercial Web sites without using the government-funded network. By the end of 1992, the first commercial online service provider, Delphi, offered full Internet access to its subscribers, and several other providers followed. In June 1993, the Web boasted just 130 sites. By a year later, the number had risen to nearly 3,000. By April 1998, there were more than 2.2 million sites on the Web. Today, the Internet is a public, cooperative, and self-sustaining facility accessible to hundreds of millions of people worldwide. Physically, the Internet uses a portion of the total resources of the currently existing public telecommunication networks. Technically, what distinguishes the Internet is its use of a set of protocols called TCP/IPTCP/IPTCP/IPTCP/IP (for Transmission Control Protocol/Internet Protocol). Two recent adaptations of Internet technology, the intranet and the extranet, also make use of the TCP/IP protocol.
For many Internet users, electronic mail (e-mail) has practically replaced the Postal Service for short written transactions. Electronic mail is the most widely used application on the Net. You can also carry on live "conversations" with other computer users, using Internet Relay Chat (IRC). More recently, Internet telephony hardware and software allows real-time voice conversations. The most widely used part of the Internet is the World Wide Web (often abbreviated "WWW" or called "the Web"). Its outstanding feature is hypertexthypertexthypertexthypertext, a method of instant cross-referencing. In most Web sites, certain words or phrases appear in text of a different color than the rest; often this text is also underlined. When you select one of these words or phrases, you will be transferred to the site or page that is relevant to this word or phrase. Sometimes there are buttons, images, or portions of images that are "clickable." If you move the pointer over a spot on a Web site and the pointer changes into a hand, this indicates that you can click and be transferred to another site. To view files on the Web, you need Web browsing software. You use this software to view different locations on the Web, which are known as Web pages. A group of Web pages is a Web site. The first page of a Web site is often called the home page.
Just as each household in the world has a unique address, each Web page in the world has a unique Internet address, sometimes called a URLURLURLURL. For example, the Internet address of the Windows home page is http://www.microsoft.com/windows. Terms to Be Familiar With:Terms to Be Familiar With:Terms to Be Familiar With:Terms to Be Familiar With: BrowserBrowserBrowserBrowser-----Contains the basic software you need in order to find, retrieve, view, and send information over the Internet. DownloadDownloadDownloadDownload--To copy data from a remote computer to a local computer. UploadUploadUploadUpload―To send data from a local computer to a remote computer. EEEE----mamamamailililil - E-mail (electronic mail) is the exchange of computer-stored messages by telecommunication. E-mail can be distributed to lists of people as well as to individuals. However, you can also send non-text files, such as graphic images and sound files, as attachments sent in binary streams. FilterFilterFilterFilter - Software that allows targeted sites to be blocked from view. Example: X- Stop, AOL@School
Home PageHome PageHome PageHome Page - The beginning "page" of any site. HTML (HyperText Markup Language)HTML (HyperText Markup Language)HTML (HyperText Markup Language)HTML (HyperText Markup Language) - The coding language used to create documents for use on the World Wide Web. There are three-letter suffixes used in coding that help to identify the type location one is viewing HTTP (HyperText Transport Protocol)HTTP (HyperText Transport Protocol)HTTP (HyperText Transport Protocol)HTTP (HyperText Transport Protocol) - the set of rules for exchanging files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. Relative to the TCP/IP suite of protocols (which are the basis for information exchange on the Internet), HTTP is an application protocol. HypertextHypertextHypertextHypertext - Generally any text that contains "links" to other text. Search EngineSearch EngineSearch EngineSearch Engine - A web server that collects data from other web servers and puts it into a database (much like an index), it provides links to pages that contain the object of your search. TCP/IPTCP/IPTCP/IPTCP/IP -------- TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP. URL (Uniform Resource Locator)URL (Uniform Resource Locator)URL (Uniform Resource Locator)URL (Uniform Resource Locator) - The Internet address. The prefix of a URL indicates which area of the Internet will be accessed. URLs look differently depending on the Internet resource you are seeking.
WWW (World Wide Web)WWW (World Wide Web)WWW (World Wide Web)WWW (World Wide Web) - A technical definition of the World Wide Web is: all the resources and users on the Internet that are using the Hypertext Transfer Protocol (HTTP). What is a Web Browser?What is a Web Browser?What is a Web Browser?What is a Web Browser? Ans.Ans.Ans.Ans. A Web browser contains the basic software you need in order to find, retrieve, view, and send information over the Internet. This includes software that lets you: • Send and receive electronic-mail (or e-mail) messages worldwide nearly instantaneously. • Read messages from newsgroups (or forums) about thousands of topics in which users share information and opinions. • Browse the World Wide Web (or Web) where you can find a rich variety of text, graphics, and interactive information. The most popular browsers are Microsoft Internet Explorer and Netscape Navigator . The appearance of a particular Web site may vary slightly depending on the browser you use. Exploring the Internet using Microsoft Internet ExplorerExploring the Internet using Microsoft Internet ExplorerExploring the Internet using Microsoft Internet ExplorerExploring the Internet using Microsoft Internet Explorer Start Internet Explorer by double-clicking the icon on your desktop.
Internet Explorer opens to the homepage set as the default. Status Bar: Watch the left side of the bar for Web-page loading progress. The right side tells you which security zone the current page is in, and shows a lock icon if you are on a secure site. Frames Scroll Bars Title Bar Menu BarStandard Buttons Toolbar Address Bar Transmission Status—Windows logo changes to a rotating globe until the Web site is located.
ToolbarsToolbarsToolbarsToolbars The Microsoft Internet Explorer toolbar consists of buttons that are shortcuts for menu commands. They make browsing faster and easier. Internet Explorer 5.5 Standard Buttons Toolbar:Internet Explorer 5.5 Standard Buttons Toolbar:Internet Explorer 5.5 Standard Buttons Toolbar:Internet Explorer 5.5 Standard Buttons Toolbar: 1. Back.Back.Back.Back. Lets you return to pages you've viewed, beginning with the most recent. Right-click the Back button and select from a list of recently visited sites. 2. Forward.Forward.Forward.Forward. Lets you move forward through pages you've viewed using the Back button. Right-click the Forward button and select from a list of recently visited sites. 3. Stop.Stop.Stop.Stop. Halts the process of downloading a Web page. Click this if you want to stop downloading a page for any reason for example, if you're having trouble downloading it or if you don't want to wait for it to download. Then try downloading it again or browse elsewhere. 4. Refresh.Refresh.Refresh.Refresh. Updates any Web page stored in your disk cache with the latest content. When you return to a page that you've visited, your browser displays the file stored in your disk cache, rather than the current page on the World Wide Web. If a web page doesn't come up the whole way or is taking abnormally long to load, try the Refresh or Reload button - sometimes this will load the page better. 1 2 3 4 5 6 7 8 9 10 12 13 1411
5. Home.Home.Home.Home. Returns you to your home page. You can designate any Web page as your home page. 6. Search.Search.Search.Search. Displays a choice of popular Internet search engines in the left pane. Your search results appear in the left pane, too. When you click a link, the page appears in the right pane, so you don't lose sight of your search results. 7. Favorites.Favorites.Favorites.Favorites. Displays a list of the sites you have marked. Click any item in the list to jump to it. 8. History.History.History.History. Shows a list of Web sites you've visited. 9. Mail.Mail.Mail.Mail. Connects you to the Microsoft Outlook Express messaging and collaboration client so you can read e-mail and newsgroup messages. 10. Print.Print.Print.Print. Prints the page you're viewing. This is one way to save information from the Internet so that you don't have to reconnect to view it again. You can even print the URL associated with each hyperlink, making it easy to navigate to the site later. 11. Edit.Edit.Edit.Edit. Opens a file in the Microsoft Word word processor that contains the HTML code for the page you're viewing so you can see and even edit it. 12. Discussion.Discussion.Discussion.Discussion. Access a discussion server. 13. Messenger.Messenger.Messenger.Messenger. Opens Windows Messenger.
14. Media.Media.Media.Media. Displays a list of audio and video media options using Real Player or the Windows Media Player. What is a URL?What is a URL?What is a URL?What is a URL? Ans. Every server on the Internet has an IP number, a unique number consisting of 4 parts separated by dots. The IP number is the server's address. 165.113.245.2 128.143.22.55 However, it is harder for people to remember numbers than to remember word combinations. So, addresses are given "word-based" addresses called URLs. The URL and the IP number are one and the same. The standard way to give the address of any resource on the Internet that is part of the World Wide Web (WWW). A URL looks like this: http://www.matisse.net/seminars.html telnet://well.sf.ca.us gopher://gopher.ed.gov/ The URL is divided into sections: transfer/transport protocol :// server (or domain). generic top level domain/path/filename The first part of a URL defines the transport protocol.
http://http://http://http:// (HyperText Transport Protocol) moves graphical, hypertext files ftp://ftp://ftp://ftp:// (File Transfer Protocol) moves a file between 2 computers gopher://gopher://gopher://gopher:// (Gopher client) moves text-based files news:news:news:news: (News group reader) accesses a discussion group telnet:/telnet:/telnet:/telnet:///// (Telnet client) allows remote login to another computer Here's an example: http://www.vrml.k12.la.us/tltc/mainmenu.htm • httphttphttphttp is the protocol • www.vrml.k12.la.uswww.vrml.k12.la.uswww.vrml.k12.la.uswww.vrml.k12.la.us is the server • tltc/tltc/tltc/tltc/ is the path • mainmenu.htmmainmenu.htmmainmenu.htmmainmenu.htm is the filename of the page on the site 1. You do not have to enter http://http://http://http:// , most browsers will add that information when you press EnterEnterEnterEnter or click the button at the end of the Address Bar. 2. To view recently visited Web sites, click the down arrow at the end of the address field.
3. When you start typing a frequently used Web address in the Address bar, a list of similar addresses appears that you can choose from. And if a Web-page address is wrong, Internet Explorer can search for similar addresses to try to find a match. 4. The URL mmmmustustustust be typed correctly. If you get a “Server Does Not Have A DNS Entry” message, this message tells you that your browser can't locate the server (i.e. the computer that hosts the Web page). It could mean that the network is busy or that the server has been removed or taken down for maintenance. Check your spelling and try again later. What are Domains?What are Domains?What are Domains?What are Domains? Ans. Domains divide World Wide Web sites into categories based on the nature of their owner, and they form part of a site's address, or uniform resource locator (URL). Common top-level domains are: .com.com.com.com―commercial enterprises .mil.mil.mil.mil―military site .org.org.org.org―organization site (non-profits, etc.) .int.int.int.int―organizations established by international treaty .net.net.net.net―network .biz.biz.biz.biz―commercial and personal .edu.edu.edu.edu―educational site (universities, schools, etc.) .info.info.info.info―commercial and personal .gov.gov.gov.gov―government organizations .name.name.name.name―personal sites
Additional three-letter, four-letter, and longer top-level domains are frequently added. Each country linked to the Web has a two-letter top-level domain, for example .fr is France, .ie is Ireland.
The BasicsThe BasicsThe BasicsThe Basics of HTMLof HTMLof HTMLof HTML Welcome to Lesson ! Modifying existing web pages does not have to be difficult. There is no need to learn the entire HTML programming language as this tutorial is designed to provide a general understanding of the codes. In this lesson the following basic definitions and relevant tags are discussed: • What is HTML? • What are Tags? • Explanation of Document Structure • Explanation of Document Structure Tags What is HTML? HTML (Hyper Text Markup Language) is the language used to write Web pages which consists of codes (tags) embedded in the text of a document. What are Tags? Tags are codes in an HTML document which the browser reads and then interprets for subsequent display to a reader. Tags are not visible when an HTML document is viewed in a browser, but their effects are. Tags begin with the opening symbol "<" and end with the closing symbol ">"; and usually come in pairs, one that begins an action and one that ends it. Below is an example of an HTML tag and its respective browser display: HTML Code Browser Display I want to <B> emphasize </B> this! I want to emphasizeemphasizeemphasizeemphasize this!
Explanation of Document Structure Each HTML document has a minimum number of tags. Here is the very least HTML code that can be called a "page": <HTML> <HEAD> <TITLE>This is my page Title!</TITLE> </HEAD> <BODY> This is my message to the world! </BODY> </HTML> NOTE: HTML is not case sensitive. <title> is equivalent to <TITLE> or <TiTlE>. Explanation of Document Structure Tags <HTML>...</HTML> Encloses the entire HTML document.These tags let the browser know to start reading and displaying the information presented within. <HEAD>...</HEAD> The <HEAD> element contains all information about the document in general. It contains HTML elements that describe the document's
usage and relationship with other documents. <TITLE>...</TITLE> The <TITLE> is contained in the <HEAD> of the document. It is displayed at the top of the browser window and on the bookmark list, so it is important to choose something descriptive, unique, and relatively short. <BODY>...</BODY> The <BODY> element contains all the information which is part of the document. There are a number of different attributes for the <BODY> tag (attributes are the elements included within brackets that change the behavior or appearance of a tag). They are: "BACKGROUND=" Specifies the image tile that is to appear in the document's background. EXAMPLE: <BODY BACKGROUND= "picturename.gif"> </BODY> "BGCOLOR=" Sets the background color of the page. In order to do this a six digit hexadecimal number denoting a red-green-blue color value is included. Thus "000000" is black and "FFFFFF" is white and every other colour in between is described using these 6 characters in different combination. In addition to the hexadecimal system, there are sixteen color names that (other than black) that can be included in the tags. They are: Aqua, Red, Green, Blue, Violet,
Fuchsia, Gray, Lime, Maroon, Navy, Olive, Purple, Silver, Teal, White, and Yellow. EXAMPLE: <BODY BGCOLOR="#FFFFFF"> This page has a white background. </BODY> OR EXAMPLE: <BODY BGCOLOR="WHITE"> This page has a white background. </BODY> "LINK=" Sets the hexadecimal color code for links that have not yet been visited. EXAMPLE: <BODY LINK="#0C6249"> This page has blue links </BODY> VLINK= Sets the hexadecimal color code for links the user has already visited. EXAMPLE: <BODY VLINK="#800080"> This page has purple links after being visited </BODY> "ALINK=" Sets color of links that are active (ie.,
the color they turn when the link is clicked on). EXAMPLE: <BODY ALINK="#FFB50C"> This page has yellow active links </BODY> "TEXT=" Sets the hexadecimal color code for the default text color. EXAMPLE: <BODY TEXT="#00006A"> This page has blue text </BODY> The <BODY> tags for this document are as follows: <BODY BACKGROUND="spiral_ruled.gif" BGCOLOR="#FFFFFF" TEXT="#00006A" LINK="#005A5A" VLINK="800080" ALINK="#FFB50C"> An excellent way to learn HTML is to view the coding used on other web pages. To do this in either Netscape or Internet Explorer - select "View Source" from the "View" menu. The file contents with all the HTML tags will be displayed in a new window. Try it out!
In the Box below, type the following HTML code, then click the "View" button. The HTML document you made will be displayed in a new browser window. You may wish to experiment by changing the words within the tags. Try typing this: <HTML> <HEAD> <TITLE>My first Web page</TITLE> </HEAD> <BODY BGCOLOR="#800080" TEXT="#FFFFFF"> Type a message here. </BODY> </HTML>
What is HTML ?What is HTML ?What is HTML ?What is HTML ? Before your begin:Before your begin:Before your begin:Before your begin: Before you begin, it's important that you know Windows or Unix. A working knowledge of Windows or Unix makes it much easier to learn HTML. You should be familiar with: • Basic word processing using any text editor. • How to create directories and files. • How to navigate through different directories. • Basic understanding on internet browsing using a browser like Internet Explorer or Firefox etc. • Introducing HTML:Introducing HTML:Introducing HTML:Introducing HTML: HTML stands for HHHHyperttttext MMMMarkup LLLLanguage, and it is the most widely used language to write Web Pages. As its name suggests, HTML is a markup language. • HypertextHypertextHypertextHypertext refers to the way in which Web pages (HTML documents) are linked together. When you click a link in a Web page, you are using hypertext. • Markup LanguageMarkup LanguageMarkup LanguageMarkup Language describes how HTML works. With a markup language, you simply "mark up" a text document with tags that tell a Web browser how to structure it to display. Originally, HTML was developed with the intent of defining the structure of documents like headings, paragraphs, lists, and so forth to facilitate the sharing of scientific information between researchers. All you need to do to use HTML is to learn what type of markup to use to get the results you want. Creating HTML Document:Creating HTML Document:Creating HTML Document:Creating HTML Document:
Creating an HTML document is easy. To begin coding HTML you need only two things: a simple-text editor and a web browser. Notepad is the most basic of simple- text editors and you will probably code a fair amount of HTML with it. You can use our HTML Online Editor to learn HTML. Here are the simple steps to create a baisc HTML document: • Open Notepad or another text editor. • At the top of the page type <html>. • On the next line, indent five spaces and now add the opening header tag: <head>. • On the next line, indent ten spaces and type <title> </title>. • Go to the next line, indent five spaces from the margin and insert the closing header tag: </head>. • Five spaces in from the margin on the next line, type<body>. • Now drop down another line and type the closing tag right below its mate: </body>. • Finally, go to the next line and type </html>. • In the File menu, choose Save As. • In the Save as Type option box, choose All Files. • Name the file template.htm. • Click Save. You have basic HTML document now, to see some result put the following code in title and body tags. <html><html><html><html> <head><head><head><head> <title>This is document title</title><title>This is document title</title><title>This is document title</title><title>This is document title</title> </head></head></head></head> <body><body><body><body> <h1>This is a heading</h1><h1>This is a heading</h1><h1>This is a heading</h1><h1>This is a heading</h1> <p>Document de<p>Document de<p>Document de<p>Document description goes here.....</p>scription goes here.....</p>scription goes here.....</p>scription goes here.....</p> </body></body></body></body>
</html></html></html></html> Now you have created one HTML pageHTML pageHTML pageHTML page and you can use a Web Browser to open this HTML file to see the result. Hope you understood that Web Pages are nothing but they are simple HTML files with some content which can be rendered using Web Browsers. Here <html>, <head>,…<p>, <h1> etc. are called HTML tags. HTML tags are building blocks of an HTML document and we will learn all the HTML tags in subsequent chapters. NOTE:NOTE:NOTE:NOTE: One HTML file can have extension as .htm.htm.htm.htm or .h.h.h.htmltmltmltml. So you can use either of them based on your comfort. HTML Document Structure:HTML Document Structure:HTML Document Structure:HTML Document Structure: An HTML document starts and ends with <html> and >/html> tags. These tags tell the browser that the entire document is composed in HTML. Inside these two tags, the document is split into two sections: • The <head>…</head> elements, which contain information about the document such as title of the document, author of the document etc. Information inside this tag does not display outside. • The <body>…</body> elements, which contain the real content of the document that you see on your screen. HTML Tags and Elements:HTML Tags and Elements:HTML Tags and Elements:HTML Tags and Elements: HTML language is a markup language and we use many tags to markup text. In the above example you have seen <html>, <body> etc. are called HTML tags or HTML elements. Every tag consists of a tag name, sometimes followed by an optional list of tag attributes , all placed between opening and closing brackets (< and >). The simplest tag is nothing more than a name appropriately enclosed in brackets, such as <head> and <i>. More complicated tags contain one or more attributes , which specify or modify the behavior of the tag.
According to the HTML standard, tag and attribute names are not case-sensitive. There's no difference in effect between <head>, <Head>, <HEAD>, or even <HeaD>; they are all equivalent. But with XHTML, case is important: all current standard tag and attribute names are in lowercase. HTML is Forgiving?HTML is Forgiving?HTML is Forgiving?HTML is Forgiving? A very good quality associated with all the browsers is that they would not give any error if you have not put any HTML tag or attribute properly. They will just ignore that tag or attribute and will apply only correct tags and attributes before displaying the result. We can not say, HTML is forgiving because this is just a markup language and required to format documents. What is HTML ?What is HTML ?What is HTML ?What is HTML ? Before your begin:Before your begin:Before your begin:Before your begin: Before you begin, it's important that you know Windows or Unix. A working knowledge of Windows or Unix makes it much easier to learn HTML. You should be familiar with: • Basic word processing using any text editor. • How to create directories and files. • How to navigate through different directories. • Basic understanding on internet browsing using a browser like Internet Explorer or Firefox etc. Introducing HTML:Introducing HTML:Introducing HTML:Introducing HTML: HTML stands for HHHHyperttttext MMMMarkup LLLLanguage, and it is the most widely used language to write Web Pages. As its name suggests, HTML is a markup language.
• HypertextHypertextHypertextHypertext refers to the way in which Web pages (HTML documents) are linked together. When you click a link in a Web page, you are using hypertext. • Markup LaMarkup LaMarkup LaMarkup Languagenguagenguagenguage describes how HTML works. With a markup language, you simply "mark up" a text document with tags that tell a Web browser how to structure it to display. Originally, HTML was developed with the intent of defining the structure of documents like headings, paragraphs, lists, and so forth to facilitate the sharing of scientific information between researchers. All you need to do to use HTML is to learn what type of markup to use to get the results you want. Creating HTML Document:Creating HTML Document:Creating HTML Document:Creating HTML Document: Creating an HTML document is easy. To begin coding HTML you need only two things: a simple-text editor and a web browser. Notepad is the most basic of simple- text editors and you will probably code a fair amount of HTML with it. You can use our HTML Online Editor to learn HTML. Here are the simple steps to create a baisc HTML document: • Open Notepad or another text editor. • At the top of the page type <html>. • On the next line, indent five spaces and now add the opening header tag: <head>. • On the next line, indent ten spaces and type <title> </title>. • Go to the next line, indent five spaces from the margin and insert the closing header tag: </head>. • Five spaces in from the margin on the next line, type<body>. • Now drop down another line and type the closing tag right below its mate: </body>. • Finally, go to the next line and type </html>. • In the File menu, choose Save As.
• In the Save as Type option box, choose All Files. • Name the file template.htm. • Click Save. You have basic HTML document now, to see some result put the following code in title and body tags. <html><html><html><html> <head><head><head><head> <title>This is document title</title><title>This is document title</title><title>This is document title</title><title>This is document title</title> </head></head></head></head> <body><body><body><body> <h1>This is a heading</h1><h1>This is a heading</h1><h1>This is a heading</h1><h1>This is a heading</h1> <p>Document description goes here.....</p><p>Document description goes here.....</p><p>Document description goes here.....</p><p>Document description goes here.....</p> </body></body></body></body> </html></html></html></html> Now you have created one HTML pageHTML pageHTML pageHTML page and you can use a Web Browser to open this HTML file to see the result. Hope you understood that Web Pages are nothing but they are simple HTML files with some content which can be rendered using Web Browsers. Here <html>, <head>,…<p>, <h1> etc. are called HTML tags. HTML tags are building blocks of an HTML document and we will learn all the HTML tags in subsequent chapters. NOTE:NOTE:NOTE:NOTE: One HTML file can have extension as .htm.htm.htm.htm or .html.html.html.html. So you can use either of them based on your comfort. HTML Document Structure:HTML Document Structure:HTML Document Structure:HTML Document Structure: An HTML document starts and ends with <html> and >/html> tags. These tags tell the browser that the entire document is composed in HTML. Inside these two tags, the document is split into two sections:
• The <head>…</head> elements, which contain information about the document such as title of the document, author of the document etc. Information inside this tag does not display outside. • The <body>…</body> elements, which contain the real content of the document that you see on your screen. HTML Tags and Elements:HTML Tags and Elements:HTML Tags and Elements:HTML Tags and Elements: HTML language is a markup language and we use many tags to markup text. In the above example you have seen <html>, <body> etc. are called HTML tags or HTML elements. Every tag consists of a tag name, sometimes followed by an optional list of tag attributes , all placed between opening and closing brackets (< and >). The simplest tag is nothing more than a name appropriately enclosed in brackets, such as <head> and <i>. More complicated tags contain one or more attributes , which specify or modify the behavior of the tag. According to the HTML standard, tag and attribute names are not case-sensitive. There's no difference in effect between <head>, <Head>, <HEAD>, or even <HeaD>; they are all equivalent. But with XHTML, case is important: all current standard tag and attribute names are in lowercase. HTML is Forgiving?HTML is Forgiving?HTML is Forgiving?HTML is Forgiving? A very good quality associated with all the browsers is that they would not give any error if you have not put any HTML tag or attribute properly. They will just ignore that tag or attribute and will apply only correct tags and attributes before displaying the result. We can not say, HTML is forgiving because this is just a markup language and required to format documents.
Basic elements of a communication systemBasic elements of a communication systemBasic elements of a communication systemBasic elements of a communication system Communications is the process of transferring messages from one point to another. There are three basic elements of any communications process are: 1. A sender (source) which creates the message to be transmitted. 2. A medium which carries the message. 3. A receiver (sink) which receives the message. For example, when you speak to your friend on the telephone, you are the sender. The telephone line through which your voice is transmitted is the medium and your friend is the receiver. This is a simple example of voice communication. The same concept holds good for data communications also. Data communications is the function of transporting data from one point to another. In this case, the sender and the receiver are normally machines, in particular, computer devices (computers, terminals, peripheral devices like line printers etc.) and the transmission medium may be telephone lines , satellite links etc. however, the messages that are transmitted are data, not voice conversations. Thus, the electronic systems that transfer data from one point to another are called data communication systems. Q. Explain Data transmission modes?Q. Explain Data transmission modes?Q. Explain Data transmission modes?Q. Explain Data transmission modes? Ans.Ans.Ans.Ans.
Data transmission modesData transmission modesData transmission modesData transmission modes There are three ways, or modes for transmitting data from one point to another. These are simplex, half-duplex, Full duplex. • SimplexSimplexSimplexSimplex If transmission is simplex, communication can take place in only one direction. Devices connected to such a circuit is either a send only or a receive only device. • Half DuplexHalf DuplexHalf DuplexHalf Duplex A half duplex system can transmit data in both directions, but only in one direction at a time. Thus a half duplex line can alternately send and receive data. It requires two wires. This is the most common type of transmission for voice communications because only one person is supposed to speak at a time. • Full DuplexFull DuplexFull DuplexFull Duplex In a full duplex system, the line must be “turned around” each time the direction is reversed. A full duplex system is used that allows information to flow simultaneously in both directions on the transmission path. Q. Explain Bandwidth, Baud Narrow band, Voice band, bQ. Explain Bandwidth, Baud Narrow band, Voice band, bQ. Explain Bandwidth, Baud Narrow band, Voice band, bQ. Explain Bandwidth, Baud Narrow band, Voice band, b There are three ways, or modes for transmitting data from one point to another. duplex, Full duplex. If transmission is simplex, communication can take place in only one direction. Devices connected to such a circuit is either a send only or a receive A half duplex system can transmit data in both directions, but only in one ction at a time. Thus a half duplex line can alternately send and receive data. It requires two wires. This is the most common type of transmission for voice communications because only one person is supposed to speak at a time. x system, the line must be “turned around” each time the direction is reversed. A full duplex system is used that allows information to flow simultaneously in both directions on the transmission path. Q. Explain Bandwidth, Baud Narrow band, Voice band, bQ. Explain Bandwidth, Baud Narrow band, Voice band, bQ. Explain Bandwidth, Baud Narrow band, Voice band, bQ. Explain Bandwidth, Baud Narrow band, Voice band, broad band?road band?road band?road band? There are three ways, or modes for transmitting data from one point to another. If transmission is simplex, communication can take place in only one direction. Devices connected to such a circuit is either a send only or a receive A half duplex system can transmit data in both directions, but only in one ction at a time. Thus a half duplex line can alternately send and receive data. It requires two wires. This is the most common type of transmission for voice communications because only one person is supposed to speak at a time. x system, the line must be “turned around” each time the direction is reversed. A full duplex system is used that allows information to flow simultaneously in both directions on the transmission path. road band?road band?road band?road band?
Ans. § Bandwidth:§ Bandwidth:§ Bandwidth:§ Bandwidth: Range of frequencies available for data transmission. It refers to data transmission rate. Higher the bandwidth, the more data it can transmit. § Baud:§ Baud:§ Baud:§ Baud: Unit of measurement of data transfer rate. Measured in bits per second (bps). § Narrow§ Narrow§ Narrow§ Narrow----band:band:band:band: Sub-voice grade channels in range from 45 to 300 baud. Mainly used for telegraph lines and low-speed terminals. § Voice§ Voice§ Voice§ Voice----band:band:band:band: Voice grade channels with speed up to 9600 baud. Mainly used for ordinary telephone voice communication and slow I/O devices. § Broad§ Broad§ Broad§ Broad----band:band:band:band: High speed channels with speed up to 1 million baud or more. Mainly used for high-speed computer-to-computer communication or for simultaneous transmission of data. Q. Explain Data transmission Media?Q. Explain Data transmission Media?Q. Explain Data transmission Media?Q. Explain Data transmission Media? Ans.Ans.Ans.Ans. Data Transmission Media (refer P.K.Sinha, Computer Fundamental)Data Transmission Media (refer P.K.Sinha, Computer Fundamental)Data Transmission Media (refer P.K.Sinha, Computer Fundamental)Data Transmission Media (refer P.K.Sinha, Computer Fundamental) The most commonly used ones are: • TwistedTwistedTwistedTwisted----pair wire (UTP cable)pair wire (UTP cable)pair wire (UTP cable)pair wire (UTP cable)
• Coaxial cableCoaxial cableCoaxial cableCoaxial cable • Microwave systemMicrowave systemMicrowave systemMicrowave system • Communications satelliteCommunications satelliteCommunications satelliteCommunications satellite • Optical fibersOptical fibersOptical fibersOptical fibers TwistedTwistedTwistedTwisted----pair wire (UTP cable)pair wire (UTP cable)pair wire (UTP cable)pair wire (UTP cable) It consists of two identical 1 mm thick copper wires insulated and twisted together. The twisted pair cables are twisted in order to reduce crosstalk and electromagnetic induction. Advantages:Advantages:Advantages:Advantages: (i) It is easy to install and maintain. (ii) It is very inexpensive Disadvantages:Disadvantages:Disadvantages:Disadvantages: (i) It is incapable to carry a signal over long distances without the use of repeaters. (ii) Due to low bandwidth, these are unsuitable for broadband applications. FigureFigureFigureFigure---- TwistedTwistedTwistedTwisted----pair wire (UTP cablepair wire (UTP cablepair wire (UTP cablepair wire (UTP cable)))) Coaxial cableCoaxial cableCoaxial cableCoaxial cable It consists of a solid wire core surrounded by one or more foil or braided wire shields, each separated from the other by some kind of plastic insulator. It is mostly used in the cable wires. Advantages:Advantages:Advantages:Advantages: (i) Data transmission rate is better than twisted pair cables.
(ii) It provides a cheap means of transporting multi-channel television signals around metropolitan areas. Disadvantages:Disadvantages:Disadvantages:Disadvantages: (i) Expensive than twisted pair cables. (ii) Difficult to manage and reconfigure. FigureFigureFigureFigure----CoaxialCoaxialCoaxialCoaxial CableCableCableCable Microwave systemMicrowave systemMicrowave systemMicrowave system The Microwave transmission is a line of sight transmission. Microwave signals travel at a higher frequency than radio waves and are popularly used for transmitting data over long distances. Advantages:Advantages:Advantages:Advantages: (i) It is cheaper than laying cable or fiber. (ii) It has the ability to communicate over oceans. Disadvantages:Disadvantages:Disadvantages:Disadvantages: (i) Microwave communication is an insecure communication. (ii) Signals from antenna may split up and transmitted in different way to different antenna which leads to reduce to signal strength. (iii) Microwave propagation is susceptible to weather effects like rains, thunder storms etc. (iv) Bandwidth allocation is extremely limited in case of microwaves.
FigureFigureFigureFigure----Microwave SystemMicrowave SystemMicrowave SystemMicrowave System Satellite linkSatellite linkSatellite linkSatellite link The satellite transmission is also a kind of line of sight transmission that is used to transmit signals throughout the world. AdvantagesAdvantagesAdvantagesAdvantages: (i) Area covered is quite large. (ii) No line of sight restrictions such as natural mountains, tall building, towers etc. (iii) Earth station which receives the signals can be fixed position or relatively mobile. DisadvantagesDisadvantagesDisadvantagesDisadvantages: (i) Very expensive as compared to other transmission mediums. (ii) Installation is extremely complex. (iii) Signals sent to the stations can be tampered by external interference.
FigureFigureFigureFigure----Satellite SystemSatellite SystemSatellite SystemSatellite System Optical fiberOptical fiberOptical fiberOptical fiber An optical fiber consists of thin glass fibers that can carry information in the form of visible light. AdvantagesAdvantagesAdvantagesAdvantages: (i) Transmit data over long distance with high security. (ii) Data transmission speed is high (iii) Provide better noise immunity (iv) Bandwidth is up to 10 Gbps. DisadvantagesDisadvantagesDisadvantagesDisadvantages: (i) Expensive as compared to other guided media. (ii) Need special care while installation?
FigureFigureFigureFigure----Optical FiberOptical FiberOptical FiberOptical Fiber Q . What is hub?Q . What is hub?Q . What is hub?Q . What is hub? Ans.Ans.Ans.Ans. Hub is used to connect computer and other peripherals such as printers, hub or switches with other in a network. It acts as a central point for various device. It also work as a repeater. Based on their function hubs can be classified as: 1, Passive hub 2. Active hub 3. Intelligent hub Q 4Q 4Q 4Q 4 WWWWhathathathat is a web browser?is a web browser?is a web browser?is a web browser? Ans.Ans.Ans.Ans. Web browsers are mainly used to access pages of the World Wide Web. By clicking on the hypertext links on a page it is possible to jump from one Internet site to another, regardless of its location. Hypertext links are usually highlighted or different colored text, images or icons. You can check for hypertext links by moving the mouse over the area; if the mouse pointer changes its shape to that of a hand then it is a hypertext link. This jumping from one site to another using the hypertext links is called ‘net surfing” or ‘web browsing”. With web browser you can download files, play games, send and receive mail and even chat with others.
Q. What are various Topologies of connectivity computerWhat are various Topologies of connectivity computerWhat are various Topologies of connectivity computerWhat are various Topologies of connectivity computers?s?s?s? Ans.Ans.Ans.Ans. Topology is & way of connecting computers in a network. The various topologies used in networking are Bus Topology :Bus Topology :Bus Topology :Bus Topology : In this all computers or device on the network are connected to each other through a central cable called Bus. In other words computer are connected serially. But topology is best for LAN. A single coaxial cable is issued for Bus topology. Ring Topology:Ring Topology:Ring Topology:Ring Topology: In ring topology all the computers or devices are connected to each other is form a ring. In this topology no terminator is used. Signals travel is a circle, passing through each computer network. In this topology two rings are used to transmit the signal. Token passing method is used to use cables.
Star Topology :Star Topology :Star Topology :Star Topology :This is most popular topology used to connect computer and devices. In this topology all the computers or devices are connected to each other through a central concentrate or (Hub or switches). Each computer is connected directly to hub or switch. Failure of single computer does not stop the working of entire network.
Mesh TopologyMesh TopologyMesh TopologyMesh Topology: In this topology each computer or device is connected with all the computers or devices on the network by a dedicated cable Due to heavy use of cables, this is expensive. Any failure of link or device in network does not stop data Communication. Q. Explain internet Applications?Q. Explain internet Applications?Q. Explain internet Applications?Q. Explain internet Applications? Ans.Ans.Ans.Ans.
Some of the important services provided by Internet are: World Wide WebWorld Wide WebWorld Wide WebWorld Wide Web (WWW):(WWW):(WWW):(WWW): It is a subset of the Internet and it presents text, images, animation, video, sound, and other multimedia in a single interface. The operation of the Web relies primarily on hypertext, as it is a means of information retrieval. Electronic Mail (EElectronic Mail (EElectronic Mail (EElectronic Mail (E----MMMMail):ail):ail):ail): It is the process of exchanging messages electronically, via a communications network, using the computer. File Transfer Protocol (FTP):File Transfer Protocol (FTP):File Transfer Protocol (FTP):File Transfer Protocol (FTP): It is a system of rules and a software program that enables a user to log on to another computer and transfer information between it and his/her computer. Telnet:Telnet:Telnet:Telnet: It connects one machine to another in such a way that a person may interact with another machine as if it is being used locally. Internet Relay Chat (IRC):Internet Relay Chat (IRC):Internet Relay Chat (IRC):Internet Relay Chat (IRC): This service allows people to communicate in real time and carry on conversations via the computer with one or more people. It provides
the user with the facility to engage in simultaneous (synchronous) online 'conversations' with other users from anywhere in the world. Chatting and Instant Messaging:Chatting and Instant Messaging:Chatting and Instant Messaging:Chatting and Instant Messaging: Chat programs allow users on the Internet to communicate with each other by typing in real time. Instant messaging allows a user on the Web to contact another user currently logged in and type a conversation. Internet Telephony:Internet Telephony:Internet Telephony:Internet Telephony: It refers to the use of the Internet rather than the traditional telephone company infrastructure, to exchange spoken or other telephonic information. Video Conferencing:Video Conferencing:Video Conferencing:Video Conferencing: It uses the same technology as IRC, but also provides sound and video pictures. It enables direct face-to-face communication across networks via web cameras, microphones, and other communication tools. Commerce through Internet:Commerce through Internet:Commerce through Internet:Commerce through Internet: It refers to buying and selling goods and services online. Newsgroups (Usenet):Newsgroups (Usenet):Newsgroups (Usenet):Newsgroups (Usenet): It is an international discussion group that focuses on a particular topic and helps in gathering information about that topic. Mailing Lists (List server):Mailing Lists (List server):Mailing Lists (List server):Mailing Lists (List server): It refers to a large community of individuals who carry out active discussions, organized around topic-oriented forums that are distributed via e-mail and this method is known as mailing list. Q. Explain Static & Dynamic Components?Q. Explain Static & Dynamic Components?Q. Explain Static & Dynamic Components?Q. Explain Static & Dynamic Components? Ans.Ans.Ans.Ans. DATA OVER INTERNETDATA OVER INTERNETDATA OVER INTERNETDATA OVER INTERNET
• The data, in terms of Internet, primarily comprises the hypertext documents containing links that connects to other documents or files. • These documents may even include animations, and multimedia components. We can divide the displayed data into two categories: Static ComponentStatic ComponentStatic ComponentStatic Component – Static component includes the information displayed on the browser that does not interact with the user. Dynamic ComponentDynamic ComponentDynamic ComponentDynamic Component – Dynamic component imparts life to a web page. This component refers to a specification by which a user can interact with a web server. Some of the programming languages (often called scripts) used to provide dynamism to a web page are Perl, JavaScript and Jscript, VBScript, Active Server Pages (ASP), PHP, XML, Java, and so on. Q. What is Netiquette?Q. What is Netiquette?Q. What is Netiquette?Q. What is Netiquette? Ans. Netiquette: Communicating online, whether by e-mail, chat rooms or message boards, is informal, quick, and easy. Netiquettes are rules that should be followed while communicating over the Internet. Dis-obeying netiquettes while sending e- mail can create trouble. Like e-mail and other online communication, the rules of netiquette are short and to the point. Q. What is Search engineQ. What is Search engineQ. What is Search engineQ. What is Search engine????
Ans.Ans.Ans.Ans. SEARCH ENGINESSEARCH ENGINESSEARCH ENGINESSEARCH ENGINES A search engine is a searchable database of Internet files which allows the user to enter keywords relating to particular topic and retrieve information about Internet sites containing those keywords. Searching the Internet: Some of the well-known search engines are www.google.com, www.hotbot.com, www.lycos.com, and www.altavista.com. Refining the Search: The major search engines allow the user to choose whether to search for the exact typed phrase, all the words in the phrase, any of the words in a phrase, and so on. Q. How EQ. How EQ. How EQ. How E----Mail Works?Mail Works?Mail Works?Mail Works? Ans.Ans.Ans.Ans. How EHow EHow EHow E----mail Worksmail Worksmail Worksmail Works: To send e-mail, one needs a connection to the Internet and access to a mail server, which forwards the mail. The standard protocol used for sending Internet e-mail is called SMTP (Simple Mail Transfer Protocol). It works in conjunction with POP (Post Office Protocol) and IMAP (Internet Mail Access Protocol) servers.
FigureFigureFigureFigure----How EHow EHow EHow E----mail System Worksmail System Worksmail System Worksmail System Works ELECTRONICELECTRONICELECTRONICELECTRONIC MAIL (EMAIL (EMAIL (EMAIL (E----MAIL)MAIL)MAIL)MAIL) Electronic mail or e-mail can be defined as the process of exchanging messages electronically, through a communications network, using the computer. It provides instant delivery of information and the ability to send file attachments by using the Internet. E-mail Address Structure: A typical e-mail address would look like: username@website.com
Login at Mail Server Checking EChecking EChecking EChecking E----mails:mails:mails:mails: One can read received e-mails by opening his/her e-mail account. Sending ESending ESending ESending E----mails:mails:mails:mails: One of the important functions of an e-mail service is to provide a platform to send e-mails. A user can reply to the received e-mail or send a new e- mail. EEEE----mail Attachments:mail Attachments:mail Attachments:mail Attachments: To send or receive files like compressed (.ZIP) files or any executable (.EXE) files you need to ‘attach’ them in your e-mails. Q. What are various types of Network explain?What are various types of Network explain?What are various types of Network explain?What are various types of Network explain? Ans.Ans.Ans.Ans. Today, when talking about networks, we are generally referring to three primary categories: Local Area Network (LAN):Local Area Network (LAN):Local Area Network (LAN):Local Area Network (LAN): LAN spans only a small geographical area such as an office, home, or building. In LAN one computer is designated as the file server, which stores all the software that controls the network and other computers connected are called workstations. Metropolitan Area Network (MAN):Metropolitan Area Network (MAN):Metropolitan Area Network (MAN):Metropolitan Area Network (MAN): MAN is a network of computers spread over a metropolitan area such as city and its suburbs. Operated by one organization (a corporate with several offices in one city), or be shared resources used by several organizations in the same city. Wide Area NetworWide Area NetworWide Area NetworWide Area Network (WAN):k (WAN):k (WAN):k (WAN): WAN is a system of interconnecting computers over a large geographical area such as cities, states, countries, or even the world. These
kinds of networks use telephone lines, satellite links, and other long-range communications technologies to connect. Q. Explain Communication Protocol?Q. Explain Communication Protocol?Q. Explain Communication Protocol?Q. Explain Communication Protocol? Ans.Ans.Ans.Ans. Communication protocolCommunication protocolCommunication protocolCommunication protocol A protocol is a set of rules and procedures established to control transmission between two points so that the receiver can properly interpret the bit stream transmitted by the sender. it provides a method for orderly and efficient exchange of data by establishing rules for the proper interpretation of controls and data transmitted as raw bits and bytes. Roles of protocolRoles of protocolRoles of protocolRoles of protocol Data sequencingData sequencingData sequencingData sequencing It refers to breaking a long transmission into smaller blocks and maintaining control. That is, a long message is slit up into smaller packets of fixed size. These packets are further fragmented into data frames. This technique is widely used in conjunction with error control techniques to reduce the amount of data that must be retransmitted in case of a detected error. Data routingData routingData routingData routing Routing algorithms are designed to find the most efficient paths between sources and destinations. They can handle varying degrees of traffic on the present network configuration with optimal time utilization. Normally, they are dynamic enough to accommodate network changes and growth. Flow controlFlow controlFlow controlFlow control
A communication protocol also prevents a fast sender from overwhelming a slow receiver. It ensures resource sharing and protection against congestion by regulating the flow of data on the communication lines. Error controlError controlError controlError control Error detecting and recovering routines are also an important element of communication protocols. The most common method for correcting errors is to retransmit a block. This method requires coordination of the two stations that the block having error is discarded by the receiving station and is repeated by the transmitting station. Precedence and order of transmissionPrecedence and order of transmissionPrecedence and order of transmissionPrecedence and order of transmission There are well defined rules to condition all stations about when to transmit their data and when to receive data from other stations. It is ensured that all stations get a chance to use the communication lines and other resources of the network depending upon the priorities assigned to them. ConnectioConnectioConnectioConnection establishmentn establishmentn establishmentn establishment When two stations of a network want to communicate with each other, the communication protocol establishes and verifies a connection between the two. Data securityData securityData securityData security Providing data security and privacy is also built into most communications software packages. It prevents access of data by unauthorized users because it is relatively easy to tap a data communication line. Log informationLog informationLog informationLog information Data communications software can also develop log information which consists of all jobs and data communications tasks that have taken place. Such information is normally used for financial purposes and the various users of the network are charged accordingly. Q. Explain ISO/OSI Model?Q. Explain ISO/OSI Model?Q. Explain ISO/OSI Model?Q. Explain ISO/OSI Model? Ans.Ans.Ans.Ans.
ISO/OSI ModelISO/OSI ModelISO/OSI ModelISO/OSI Model The initial computer networks had their own set of standards and conventions that were quite hardware oriented. Each manufacturer used to develop their own communications protocols for their network. thus the data communication protocols of one network were not compatible with any other network. this problem was recognized by the International Standard organization(ISO) which established a sub-committee to develop an international standard on network architectures. The result was the open system interconnection (OSI) model, which is a framework for defining standards for linking heterogeneous computers in a packet switched network. The OSI model is also designed in a highly structured way. It is 7-layer architecture and defines a separate set of protocols for each layer. Physical layerPhysical layerPhysical layerPhysical layer---- The physical layer covers the physical interface between devices. It defines the electrical and mechanical aspects of interfacing to a physical medium for transmitting data. it also defines how physical links are set up, maintained and disconnected. In other words, it deals with the mechanical, electrical, procedural and functional characteristics of transmission. Data link layerData link layerData link layerData link layer---- The data link layer is responsible for establishing an error-free communications path between computers over the physical channel. It splits packets into data frames which are transmitted sequentially by the ender and the receiver transmits the acknowledgement. Network layerNetwork layerNetwork layerNetwork layer----
Set up the logical path between the source and the destination computers of the network. The message to be transmitted is first fragmented into packets at this layer. Then it performs sequencing and error control of these packets .thus the routing decisions are taken at the network layer. Transport layerTransport layerTransport layerTransport layer---- Once a path is established between the sending and the receiving stations, the transport layer provides control standards for a communication session for enabling processes to exchange data reliably and sequentially. Session layerSession layerSession layerSession layer---- The session layer provides means of establishing, maintaining and terminating a dialogue or a session between two end users. Presentation layerPresentation layerPresentation layerPresentation layer---- The presentation layer provides facilities to convert encoded transmitted data into displyable form for being displayed on a printer. Application layerApplication layerApplication layerApplication layer---- This is a user oriented layer which provides services that directly support the end user of the network. Q. What are important features of HTML?Q. What are important features of HTML?Q. What are important features of HTML?Q. What are important features of HTML? Ans.Ans.Ans.Ans. Features ofFeatures ofFeatures ofFeatures of HTMLHTMLHTMLHTML
1. Simple:1. Simple:1. Simple:1. Simple: It is simplest web developer tools. All the tags are self explanatory i.e. their meaning is clear from their name. For, example ‘B’ means bold, ‘I’ means italics and U means underline. 2. Supports all types of documents:2. Supports all types of documents:2. Supports all types of documents:2. Supports all types of documents: It can support all types of documents like text documents, sound and multimedia. 3. Need no compilation:3. Need no compilation:3. Need no compilation:3. Need no compilation: The languages like C/C++ requires compilation before doing anything with programs but HTML codes are automatically complied and results are displayed on screen. 4. Supported by browser:4. Supported by browser:4. Supported by browser:4. Supported by browser: All most all types of browsers supports the HTML code like Microsoft internet explorer ‘and Netscape navigation’ gold. 5. Compatibility with other web tools:5. Compatibility with other web tools:5. Compatibility with other web tools:5. Compatibility with other web tools: The code written in HTML can be pasted in other web tools and run efficiently without any change. For example HTML code can be pasted in Front page 2000, flash, dream weaver etc. 6. Extendibility:6. Extendibility:6. Extendibility:6. Extendibility: adding features in it can enhance The HTML code. We can extend it using DHTML etc. 7. Internet Base:7. Internet Base:7. Internet Base:7. Internet Base: It is the first web tool and all the Internet tools are based upon the idea of HTML. 8. Developing intranet or extranet sites:8. Developing intranet or extranet sites:8. Developing intranet or extranet sites:8. Developing intranet or extranet sites: HTML is commonly used to develop intranet and extranet sites, which are accessed by company people from one or more locations. 9. Developing help files:9. Developing help files:9. Developing help files:9. Developing help files: It is used to develop on-line help files and help the developers to produce help documentation that is accessible from any computer and platform.
10. Developing network applications:10. Developing network applications:10. Developing network applications:10. Developing network applications: It is used to develop all types of applications such as training programs interactive charts or databases that are available,” from web. 11. Developing kiosk application:11. Developing kiosk application:11. Developing kiosk application:11. Developing kiosk application: HTML can be used to create kiosk applications― which can run on stand-alone computers with touch-screen applications. Q. 4. What re the different Versions of HTML?Q. 4. What re the different Versions of HTML?Q. 4. What re the different Versions of HTML?Q. 4. What re the different Versions of HTML? Ans. Versions of HTMLAns. Versions of HTMLAns. Versions of HTMLAns. Versions of HTML • HTML• HTML• HTML• HTML is an evolving language, and each new version is given a number. The first definitive version was HTML 2.0 ― this had most of the elements we know and love, but was missing some of the Netscape/ Microsoft extensions, and did not support tables, or ALIGN attributes. • HTML 3 (late 1995)• HTML 3 (late 1995)• HTML 3 (late 1995)• HTML 3 (late 1995) was an ambitious effort on the part of Dave Raggett to upgrade the features and utility of HTML. However, it was never completed or implemented although many features were integrated in the next “official” version of.HTML, known as HTML 3.2. • HTML 3.2• HTML 3.2• HTML 3.2• HTML 3.2 was the next official version, integrating support for TABLES, image, heading and other element ALIGN attributes, and a few other finicky details. HTML 3.2 is the current “universal” dialect ― essentially all browsers understand HTML 3.2. IT was however, missing some of the Netscape/M1crosoft extensions, such as FRAMES, EMBED and APPLET. Support for these (after fashion) came in HTML 4.0 • HTML 4.01 is• HTML 4.01 is• HTML 4.01 is• HTML 4.01 is the current official standard. it includes support for most of proprietary extension5, plus support for extra features (InternatiOfla1izel
documents, support for Cascading Style Sheets, extra TABLE, FORM, and JavaScript enhancements), that are not universally supported Q. What do you mean byQ. What do you mean byQ. What do you mean byQ. What do you mean by tag?tag?tag?tag? What are itsWhat are itsWhat are itsWhat are its types?types?types?types? Discuss with Example.Discuss with Example.Discuss with Example.Discuss with Example. Ans. HTML Tags:Ans. HTML Tags:Ans. HTML Tags:Ans. HTML Tags: HTML codes are referred to as tags. Tags open with a less-than sign and close with a greater-than sign. The less-than and greater-than signs are called brackets. <Tag> An HTML file is basically just a text file, which may contain references to other files. Angle brackets (<, >) are used to set off tags, which give information about the structure of the page. For example, the tag <p> indicates the beginning of a new paragraph. Tags are instructions that are embedded directly into the text of a HTML document. Each HTML tag describes that the browser should do something instead of simply displaying Types of TagTypes of TagTypes of TagTypes of Tag There are two kinds of HTML tags; paired and unpaired. Paired Tag:Paired Tag:Paired Tag:Paired Tag: A tag is said to be a paired tag if the text is placed between a tag and its companion tag. In paired tags, the first tag is referred to as Opening Tag and the second tag is referred to as Closing Tag. Paired tags require an opening tag that turns a formatting feature on and a closing tag that turns the feature off. Paired tags must surround the text you want formatted
with that feature. For example, <title> and </title> define a page’s title. You must include the slash in the closing tag in order for the pair to work. Always remember to close paired tags. Example:Example:Example:Example: <i> This text is in italics. </i> Here <i> is called opening tag and </i> is called closing tag. Paired TagsPaired TagsPaired TagsPaired Tags FunctionFunctionFunctionFunction <html>, </html> Indicates the page is coded in HTML. <head>, </head>, Indicates part of the document that contains Information about the page. <title>, </title> Always located in the head, the title provides the name of the document to be displayed by search engines and on browser title bars. <body>, </body> Indicates part of the document that contains Formatted text, images, and links. <hn>,</hn> Where n is a number between 1 to 6. Headings are used to arrange the contents in a systematic way. <a href>, </a> Links to another Web page or another location in the current Web page. <Ol>,</Ol> Ordered list (1, 2, 3, 4....); used with the <Ii> tag. <ul>, </ul> Unordered list (bullet points); used with the <Ii> tag. <P></P> Paragraphs may consist of a single sentence or more than one sentences including punctuation marks and blank space. All paired tags in HTML must be properly nested. This means that every closing tag must match up with the nearest preceding unmatched paired tag.
Unpaired Tag:Unpaired Tag:Unpaired Tag:Unpaired Tag: Unpaired tags work alone, and are usually placed before the text you want formatted. An unpaired tag does not have a companion tag. Unpaired tags are also known as Singular or Stand-Alone Tags. An unpaired tag sometimes also called empty ― that is, they do not affect a block of the document in some way. An example is the <HR> element, which draws a horizontal line across the page. This element would simply be entered as Example:Example:Example:Example: <br> , <hr> etc. These tags does not require any companion tag. The paired and unpaired tags are also called <tag_on> that switches the tag sequence on. For example, to bold some text add a <strong> at the beginning of the text and </tagoff> that switches the tag sequence off. The tag_on and tag_off tags are the same except the off tag has an / character in front of it. For example, to switch off the bolding add a </strong> character sequence at the end of the text that is to be given the attribute of bolding. UnpairedUnpairedUnpairedUnpaired TagTagTagTag FunctionFunctionFunctionFunction <img> Inserts an image into your text. See below for more information. <br> Line break; moves subsequent text to the beginning of the line. <hr> Horizontal rule; draws a line across the width of the page. Q.Q.Q.Q. ExplainExplainExplainExplain Basic HTML Tags?Basic HTML Tags?Basic HTML Tags?Basic HTML Tags? Ans.Ans.Ans.Ans. Basic HTML TagsBasic HTML TagsBasic HTML TagsBasic HTML Tags
The basic tags include <html>, <title>, <meta>, and <body>. We introduce each of the four in the following: <html><html><html><html> This tag is used to indicate that this is a HTML document. Most HTML documents should start and end with this tag. <head><head><head><head> This tag is used to indicate the header section of the HTML document, which typically includes the <title> and <meta> tags, and is not displayed in the main window of the browser. <title><title><title><title> This indicates the title of this HTML page. The title is what is displayed on the upper left corner of your browser when you view a web page. For example, right now you can see "Basic Tags: html, head, title, meta, body" there. That is the title of this page. The title tag is important when it comes to search engine ranking. Many of the search engines pay special attention to the text in the <title> tag. This is because (logically) that words in the <title> tag indicate what the page content is. <meta><meta><meta><meta> The <meta> tag information is not directly displayed when the page is rendered on the browser. Rather, this is used for the author of the HTML page to record information related to this page. Two common attributes are namenamenamename and contentcontentcontentcontent. The <meta> tag used to hold great importance in search engine optimization, with authors carefully drafting what's inside the tag to gain better search engine ranking, but recently its importance has been decreasing steadily. <body><body><body><body>
The <body> tag includes the HTML body of the document. Everything inside the <body> tag (other than those within the <script> tag) is displayed on the browser inside the main browser window. The <body> tag may contain several attributes. The most commonly used ones are listed below: • bgcolorbgcolorbgcolorbgcolor: This is the background color of the entire HTML document, and may be specified either by the color name directly or by the six-digit hex code. • alinkalinkalinkalink: The color of the links. • vlinkvlinkvlinkvlink: The color of the visited links. • topmargintopmargintopmargintopmargin: The margin from the top of the browser window. • leftmarginleftmarginleftmarginleftmargin: The margin from the left of the browser window. So, in general, all HTML documents have the following format: <html> <head> <title> Here is the title of the HTML document. </title> <meta name=" " content=" " /> ... (there may be one or more meta tags) </meta> </head> <body> Here is the body of the HTML document. </body> </html> More TagsMore TagsMore TagsMore Tags
In this lesson we discuss two more attributes commonly used in the formatting of HTML documents: lists and fonts. • Lists • Fonts Lists HTML provides the means for producing two types of lists: unordered (i.e., unnumbered) and ordered (i.e., numbered) lists. Unordered Lists: An unordered list typically is a bulleted list of items. This is probably the most common type of list on the Web. The <UL> tag opens an unordered list while </UL> closes it. Between these tags are placed list items with an <LI> tag as follows: HTML Code Browser Display <UL> <LI> red <LI> yellow <LI> blue </UL> • red • yellow • blue Ordered Lists: An ordered list is formatted exactly the same as an unordered list, except that <OL> tags are used instead of <UL>. In an ordered list, sequential numbers are generated automatically, as shown below: HTML Code Browser Display
<OL> <LI> purple <LI> orange <LI> green </OL> 1. purple 2. orange 3. green Note: You can "nest" lists too (ie., subdivide lists), but use this feature sparingly as too many nested items can get difficult to follow. Fonts The <FONT> tag sets a font's size, typeface and color. Font Sizes: In HTML, font sizes range from 1-7, with 1 being the smallest. Font sizes 2 and 3 are the most commonly used. If a font size is not specified the default setting is 3. • Font Size 1 • Font Size 2 • Font Size 3 • Font Size 4 • Font Size 5 • Font Size 6 • Font Size 7 Font Typefaces: When HTML was first introduced there was only one font available. And while current versions of HTML and newer browsers allow greater flexibility in specifying preferred fonts for an HTML document to be displayed in, ultimately the choice is
limited by which fonts end-users have installed on their systems (even then users may decide to set their browsers to override preferred font settings). A few commonly supported fonts are: • Arial • Lucida Sans • Times New Roman • Verdana • Helvetica • Impact • Comic Sans MS Font Colours: Using the <FONT> tag, text can be instructed to display in any colour under the sun. One must be careful though to choose a colour that is readable on whatever background colour has been selected. Text colors are chosen either according to a hexadecimal numbering system denoting a red-green-blue color value, or by specifying one of sixteen pre-defined colour names that (other than black) can be included in the <FONT> tag. These sixteen colours are: • Aqua - Aqua • Red - Red • Green - Green • Blue - Blue • Violet - Violet • Fuchsia - Fuchsia • Gray - Gray • Lime - Lime • Maroon - Maroon • Navy - Navy • Olive - Olive
• Purple - Purple • Silver - Silver • Teal - Teal • White - White • Yellow - Yellow The font attributes described above are included in the <FONT> tag as follows: HTML Code Browser Display <FONT SIZE=2>This is a size two font</FONT> This is a size two font <FONT FACE="Comic Sans MS">This font is Comic Sans MS</FONT> This font is Comic Sans MS <FONT COLOR="Fuchsia"> This text is Fuchsia </FONT> This text is Fuchsia Try it out! In the box below, type the following HTML code, then click the "View" button. The HTML document you have written will be displayed in your browser. You may wish to change some of the tags and/or attributes to experiment with some of the different items discussed in this lesson. Try typing this: <HTML>
<HEAD> <TITLE>Why I love learning HTML - Part 2</TITLE> </HEAD> <BODY BGCOLOR="#FFFFFF" TEXT="#000000"> Colors <BR> My favorite colors are: <BR> <UL> <LI><FONT SIZE=2 COLOR="NAVY" FACE="VERDANA">Navy</FONT> <LI><FONT SIZE=2 COLOR="OLIVE" FACE="VERDANA">Olive</FONT> <LI><FONT SIZE=2 COLOR="PURPLE" FACE="VERDANA">Purple</FONT> <LI><FONT SIZE=2 COLOR="TEAL" FACE="VERDANA">Teal</FONT> </UL> </BODY> </HTML> HTML FormatHTML FormatHTML FormatHTML Format This section includes the tags often used for formatting the HTML text. <font><font><font><font> The <font> tag is used to change the format of the text on the web page. The most important attributes are as follows:
• face: The type of font. Common ones include "Time New Roman", "Verdana", and "Helvetica." • size: This indicates the size of the text. This can be absolute (0 .. 6), or relative ("+1", "+2", ... or "-1", "-2" ...) • color: This indicates the color of the text. Either the color name or the six- character color code may be used to specify color. Below are some examples: Example 1 HTML: <font size=2 face="Helvetica" color=red>This illustrates the attributes of the font tag.</font> Display: This illustrates the attributes of the font tag. Example 2 HTML: <font size="+1" face="Verdana" color=AA5088>This illustrates the attributes of the font tag.</font> Display: This illustrates the attributes of the font tag. <b><b><b><b> The <b> tag will boldboldboldbold the text inside the tag. <i><i><i><i> The <i> tag will italicize the text inside the tag.
<u><u><u><u> The <u> tag will underline the text inside the tag. Here's an example using <b>, <i>, and <u>: Example 3 HTML: This <b>example</b> shows how <i>important</i> it is to use <u>tags</u>. Display: This exampleexampleexampleexample shows how important it is to use tags. Header TagsHeader TagsHeader TagsHeader Tags The header tags <h1>, ... <h6> allows us to place additional importance on the text within such tags. <h1> has the largest size, and <h6> the smallest. Many search engines put additional weight on the texts within the header tags. Example 4 HTML: <h1>This is h1 text.</h1> <h2>This is h2 text.</h2> <h3>This is h3 text.</h3> <h4>This is h4 text.</h4> <h5>This is h5 text.</h5> <h6>This is h6 text.</h6> Display: This is h1 text.This is h1 text.This is h1 text.This is h1 text.
This is h2 text.This is h2 text.This is h2 text.This is h2 text. This is h3 text.This is h3 text.This is h3 text.This is h3 text. This is h4 text.This is h4 text.This is h4 text.This is h4 text. This is h5 text.This is h5 text.This is h5 text.This is h5 text. This is h6 text.This is h6 text.This is h6 text.This is h6 text. <center><center><center><center> The <center> tag causes all the text within the tag to be centered. An example is as follows: Example 5 HTML: <center>This is centered text.</center> Display: This is centered text. <br><br><br><br> The <br> tag indicates a line break. This tag is most often used by itself, without a corresponding closing tag. <p><p><p><p> The <p> tag indicates a new paragraph. It is the same as <br><br>. This tag is most often used by itself, without a corresponding closing tag.
Rudimetary TagsRudimetary TagsRudimetary TagsRudimetary Tags This lesson introduces a number of basic tags that allow an HTML page to be formatted - much in the same way that word processors format documents. The following topics are covered: • Character Formatting
• Paragraphs • Paragraph Alignment • Forced Line Breaks • Spaces • Horizontal Rules Character Formatting: The Bold <B></B> element specifies that the enclosed text should be displayed in boldface. The Underlined <U></U> element specifies that the enclosed text should be displayed underlined. The Italic <I></I> element specifies that the enclosed text should be italicized. Below are these HTML tags beside samples of their respective browser displays: HTML Code Browser Display This text is <B>bold!</B> This text is bold!bold!bold!bold! This text is <I>italicized.</I> This text is italicized. This text is <U>underlined</U>. This text is underlined. Paragraphs In HTML you indicate paragraphs with the <P> and </P> elements. Without these elements the document becomes one long paragraph. Likewise, browsers ignore any indentations or blank lines in the HTML code.
Thus the examples below, although coded differently, are all displayed the same way: HTML Code Browser Display <P> This is a very short paragraph to illustrate my point.</P> <P>And this is the second paragraph. </P> This is a very short paragraph to illustrate my point. And this is the second paragraph. <P> Although this is written differently with lots of carriage returns it still only displays the paragraphs when you put in the Paragraph Tag.</P> <P> Like so.</P> Although this is written differently with lots of carriage returns it still only displays the paragraphs when you put in the Paragraph Tag. Like so. NOTE: The </P> closing tag may be omitted. This is because browsers understand that when they encounter a <P> tag, it means that the previous paragraph has ended. To preserve readability when composing HTML files, separate paragraphs with blank lines. As mentioned above, browsers will ignore blank spaces inserted into source code. Paragraph Alignment
Paragraph alignment can be manipulated by including either the RIGHT, LEFT, or CENTER (note the Americanized spelling) attributes within the <P> tag as shown below: HTML Code Browser Display <P ALIGN=left> This paragraph is left aligned. </P> This paragraph is left aligned. <P ALIGN=CENTER> This is a centered paragraph. </P> This is a centered paragraph. <P ALIGN=RIGHT> This paragraph is right aligned. </P> This paragraph is right aligned. Forced Line Breaks The line break tag <BR> can be used to control how browsers render text. When an HTML document is viewed the text normally does a word-wrap at the end of a line. If a text break is desired before the end of a line, use the <BR> tag to force a line break without any extra space between lines. This element has no closing tag. HTML Code Browser Display CN Tower<BR> 301 Front Street West<BR> Penthouse<BR> Toronto, Ontario M5V 2T6<BR> Canada<BR> CN Tower 301 Front Street West Penthouse Toronto, Ontario M5V 2T6 Canada
Using the <P> tag instead of the <BR> tag for short lines of text, such as the above example, would have resulted in unwanted additional white space. Horizontal Rules The horizontal rule <HR> tag produces a horizontal line the width of the browser window. Horizontal rules are useful for separating major sections of a document. The length of a rule can be varied by using the "WIDTH=" and "SIZE=" attributes. HTML Code Browser Display Horizontal Rules rule!<HR SIZE=3 WIDTH=80%> Horizontal Rules rule! There are two other attributes that can be used with the <HR> tag. They are: ALIGN= RIGHT, LEFT, or CENTER NOSHADE Causes the rule to appear solid black. Try it out! In the box below, type the following HTML code, then click the "View" button. The HTML document you have written will be displayed in your browser. You may wish to change some of the tags and/or attributes to experiment with some of the different items discussed in this lesson. Try typing this: <HTML>
<HEAD> <TITLE>HTML</TITLE> </HEAD> <BODY BGCOLOR="#800080" TEXT="#FFFFFF"> Learning HTML is <B>so</B> much fun! <P ALIGN=center> And it is really <I>easy</I> once you get the hang of it. </P> <HR SIZE=3> </BODY> </HTML> HTML Page LayoutsHTML Page LayoutsHTML Page LayoutsHTML Page Layouts
Web page layout is very important to give better look to your website. You should design your webpage layout very carefully. You may have noticed that there are many websites which have put their content in multiple columns – they are formatted like a magazine or newspaper. This is easily achieved by using tables or division or span tags. Sometime you use CSS as well to position various elements or to create backgrounds or colorful look for the pages. HTML LayoutHTML LayoutHTML LayoutHTML Layout –––– Using Tables:Using Tables:Using Tables:Using Tables: The simplest and most popular way of creating layouts is using HTML <table> tag. These tables are arranged in columns and rows, so you can utilize these rows and columns in whatever way you like. For example, the following HTML layout example is achieved using a table with 3 rows and 2 columns – but the header and footer column spans both columns using the colspan attribute: <table width="100%" border="0"><table width="100%" border="0"><table width="100%" border="0"><table width="100%" border="0"> <tr><tr><tr><tr> <td colspan="2" style="background<td colspan="2" style="background<td colspan="2" style="background<td colspan="2" style="background----color:#CC99FF;">color:#CC99FF;">color:#CC99FF;">color:#CC99FF;"> <h1>This is Web Page Main title</h1><h1>This is Web Page Main title</h1><h1>This is Web Page Main title</h1><h1>This is Web Page Main title</h1> </td></td></td></td> </tr></tr></tr></tr> <tr valign="top"><tr valign="top"><tr valign="top"><tr valign="top"> <<<<td style="backgroundtd style="backgroundtd style="backgroundtd style="background----color:#FFCCFF;color:#FFCCFF;color:#FFCCFF;color:#FFCCFF;
width:100px;textwidth:100px;textwidth:100px;textwidth:100px;text----align:top;">align:top;">align:top;">align:top;"> <b>Main Menu</b><br /><b>Main Menu</b><br /><b>Main Menu</b><br /><b>Main Menu</b><br /> HTML<br />HTML<br />HTML<br />HTML<br /> PHP<br />PHP<br />PHP<br />PHP<br /> PERL...PERL...PERL...PERL... </td></td></td></td> <td style="background<td style="background<td style="background<td style="background----color:#eeeeee;height:200px;color:#eeeeee;height:200px;color:#eeeeee;height:200px;color:#eeeeee;height:200px; width:300px;tewidth:300px;tewidth:300px;tewidth:300px;textxtxtxt----align:top;">align:top;">align:top;">align:top;"> Technical and Managerial TutorialsTechnical and Managerial TutorialsTechnical and Managerial TutorialsTechnical and Managerial Tutorials </td></td></td></td> </tr></tr></tr></tr> <tr><tr><tr><tr> <td colspan="2" style="background<td colspan="2" style="background<td colspan="2" style="background<td colspan="2" style="background----color:#CC99FF;">color:#CC99FF;">color:#CC99FF;">color:#CC99FF;"> <center><center><center><center> Copyright © 2007 Mytoptutorials.comCopyright © 2007 Mytoptutorials.comCopyright © 2007 Mytoptutorials.comCopyright © 2007 Mytoptutorials.com </center></center></center></center>
</td></td></td></td> </tr></tr></tr></tr> </table></table></table></table> This will produce following result: This is Web Page Main titleThis is Web Page Main titleThis is Web Page Main titleThis is Web Page Main title Main MenuMain MenuMain MenuMain Menu HTML PHP PERL… Technical and Managerial Tutorials Copyright © 2007 Mytoptutorials.com To Become more comfortable – Do Online Practice Multiuple Columns LayoutsMultiuple Columns LayoutsMultiuple Columns LayoutsMultiuple Columns Layouts –––– Using TablesUsing TablesUsing TablesUsing Tables You can design your webpage to put your web content in multiple pages. You can keep your content in middle column and you can use left column to use menu and right column can be used to put advertisement or some other stuff. It will be very similar to our site mytoptutorials.com. Here is an example to create three column layout: <table width="100%" border="0"><table width="100%" border="0"><table width="100%" border="0"><table width="100%" border="0"> <tr valign="top"><tr valign="top"><tr valign="top"><tr valign="top">
<td style="background<td style="background<td style="background<td style="background----color:#FFCCFF;width:20%;color:#FFCCFF;width:20%;color:#FFCCFF;width:20%;color:#FFCCFF;width:20%; texttexttexttext----align:top;">align:top;">align:top;">align:top;"> <b>Main Menu</b><br /><b>Main Menu</b><br /><b>Main Menu</b><br /><b>Main Menu</b><br /> HTML<br />HTML<br />HTML<br />HTML<br /> PHP<br />PHP<br />PHP<br />PHP<br /> PERL...PERL...PERL...PERL... </td></td></td></td> <td style="background<td style="background<td style="background<td style="background----color:#eeeeee;height:200px;color:#eeeeee;height:200px;color:#eeeeee;height:200px;color:#eeeeee;height:200px; width:60%;textwidth:60%;textwidth:60%;textwidth:60%;text----align:top;">align:top;">align:top;">align:top;"> Technical and Managerial TTechnical and Managerial TTechnical and Managerial TTechnical and Managerial Tutorialsutorialsutorialsutorials </td></td></td></td> <td style="background<td style="background<td style="background<td style="background----color:#FFCCFF;color:#FFCCFF;color:#FFCCFF;color:#FFCCFF; width:20%;textwidth:20%;textwidth:20%;textwidth:20%;text----align:top;">align:top;">align:top;">align:top;"> <b>Right Menu</b><br /><b>Right Menu</b><br /><b>Right Menu</b><br /><b>Right Menu</b><br /> HTML<br />HTML<br />HTML<br />HTML<br /> PHP<br />PHP<br />PHP<br />PHP<br />
PERL...PERL...PERL...PERL... </td></td></td></td> </tr></tr></tr></tr> <table><table><table><table> This will produce following result: MainMainMainMain MenuMenuMenuMenu HTML PHP PERL… Technical and Managerial Tutorials Right MenuRight MenuRight MenuRight Menu HTML PHP PERL… HTML LayoutsHTML LayoutsHTML LayoutsHTML Layouts –––– Using DIV, SPANUsing DIV, SPANUsing DIV, SPANUsing DIV, SPAN The div element is a block level element used for grouping HTML elements. While the div tag is a block-level element, the HTML span element is used for grouping elements at an inline level. Although we can achieve pretty nice layouts with HTML tables, tables weren't really designed as a layout tool. Tables are more suited to presenting tabular data. You can achieve same result whatever you have achieved using <table> tag in previous example. <div style="width:100%"><div style="width:100%"><div style="width:100%"><div style="width:100%"> <div style="background<div style="background<div style="background<div style="background----color:#CC99FF;">color:#CC99FF;">color:#CC99FF;">color:#CC99FF;"> <b style="font<b style="font<b style="font<b style="font----size:150%">This is Web Page Main title</b>size:150%">This is Web Page Main title</b>size:150%">This is Web Page Main title</b>size:150%">This is Web Page Main title</b> </div></div></div></div>
<div style="background<div style="background<div style="background<div style="background----color:#FFCCFF;color:#FFCCFF;color:#FFCCFF;color:#FFCCFF; height:200px;width:100px;float:left;">height:200px;width:100px;float:left;">height:200px;width:100px;float:left;">height:200px;width:100px;float:left;"> <b>Main Menu</b><br /><b>Main Menu</b><br /><b>Main Menu</b><br /><b>Main Menu</b><br /> HTML<br />HTML<br />HTML<br />HTML<br /> PHP<br />PHP<br />PHP<br />PHP<br /> PERL…PERL…PERL…PERL… </div></div></div></div> <div style="background<div style="background<div style="background<div style="background----color:#eeeeee;color:#eeeeee;color:#eeeeee;color:#eeeeee; height:200px;width:300px;float:left;">height:200px;width:300px;float:left;">height:200px;width:300px;float:left;">height:200px;width:300px;float:left;"> Technical and Managerial TutorialsTechnical and Managerial TutorialsTechnical and Managerial TutorialsTechnical and Managerial Tutorials </div></div></div></div> <div style="background<div style="background<div style="background<div style="background----color:#CC99FF;cleacolor:#CC99FF;cleacolor:#CC99FF;cleacolor:#CC99FF;clear:both">r:both">r:both">r:both"> <center><center><center><center> Copyright © 2007 MytoptutorialsCopyright © 2007 MytoptutorialsCopyright © 2007 MytoptutorialsCopyright © 2007 Mytoptutorials1111.com.com.com.com </center></center></center></center> </div></div></div></div> </div></div></div></div> This will produce following result: This is Web Page Main titleThis is Web Page Main titleThis is Web Page Main titleThis is Web Page Main title Main MenuMain MenuMain MenuMain Menu HTML PHP PERL… Technical and Managerial Tutorials Copyright © 2007 Mytoptutorials1.com Better layout can be created by using DIV, SPAN and CSS. For more information on CSS, please refer CSS Tutorial.
HTML Phrase TagsHTML Phrase TagsHTML Phrase TagsHTML Phrase Tags While some of these phrase elements are displayed in a similar manner to the <b>, <i>, <pre>, and <tt> elements you have already seen, they are designed for specific purposes. For example, the <em> and <strong> elements give text emphasis and strong emphasis respectively and there are several elements for marking up quotes. We will see all phrase tags in this section with examples. Emphasized TextEmphasized TextEmphasized TextEmphasized Text –––– The <em> Element:The <em> Element:The <em> Element:The <em> Element: The content of an <em> element is intended to be a point of emphasis in your document, and it is usually displayed in italicized text. The kind of emphasis intended is on words such as “must” in the following sentence: <<<<p>You <em>must</em> remember to close elements in XHTML.</p>p>You <em>must</em> remember to close elements in XHTML.</p>p>You <em>must</em> remember to close elements in XHTML.</p>p>You <em>must</em> remember to close elements in XHTML.</p> This will produce following result: YouYouYouYou mustmustmustmust remember to close elements in XHTML.remember to close elements in XHTML.remember to close elements in XHTML.remember to close elements in XHTML. Strong TextStrong TextStrong TextStrong Text –––– The <strong> Element:The <strong> Element:The <strong> Element:The <strong> Element: The <strong> element is intended to show strong emphasis for its content; stronger emphasis than the <em> element. As with the <em> element, the <strong> element should be used only when you want to add strong emphasis to part of a document. <p>You <strong>must</strong> remember to close elements in<p>You <strong>must</strong> remember to close elements in<p>You <strong>must</strong> remember to close elements in<p>You <strong>must</strong> remember to close elements in XHTML.</p>XHTML.</p>XHTML.</p>XHTML.</p> This will produce following result: YouYouYouYou mustmustmustmust remember to close elements in XHTML.remember to close elements in XHTML.remember to close elements in XHTML.remember to close elements in XHTML. Text AbbreviationText AbbreviationText AbbreviationText Abbreviation –––– The <abbr> Element :The <abbr> Element :The <abbr> Element :The <abbr> Element : You can indicate when you are using an abbreviated form by placing the abbreviation between opening <abbr> and closing </abbr> tags. <p>I have a frien<p>I have a frien<p>I have a frien<p>I have a friend called <abbr title=”Abhishek”>Abhy</abbr>.</p>d called <abbr title=”Abhishek”>Abhy</abbr>.</p>d called <abbr title=”Abhishek”>Abhy</abbr>.</p>d called <abbr title=”Abhishek”>Abhy</abbr>.</p> This will produce following result:
I have a friend calledI have a friend calledI have a friend calledI have a friend called Abhy.Abhy.Abhy.Abhy. Using AcronymUsing AcronymUsing AcronymUsing Acronym –––– The <acronym> Element :The <acronym> Element :The <acronym> Element :The <acronym> Element : The <acronym> element allows you to indicate that the text between an opening <acronym> and closing </acronym> element is an acronym. When possible use a title attribute whose value is the full version of the acronyms on the <acronym> element, and if the acronym is in a different language, include an xml:lang attribute in XHTML documents. <p>This chapter<p>This chapter<p>This chapter<p>This chapter covers marking up text in <acronym title=”Extensiblecovers marking up text in <acronym title=”Extensiblecovers marking up text in <acronym title=”Extensiblecovers marking up text in <acronym title=”Extensible Hypertext Markup Language”>XHTML</acronym>.</p>Hypertext Markup Language”>XHTML</acronym>.</p>Hypertext Markup Language”>XHTML</acronym>.</p>Hypertext Markup Language”>XHTML</acronym>.</p> This will produce following result: This chapter covers marking up text inThis chapter covers marking up text inThis chapter covers marking up text inThis chapter covers marking up text in XHTML.XHTML.XHTML.XHTML. At present, the major browsers do not change the appearance of the content of the <acronym> element. Special TermsSpecial TermsSpecial TermsSpecial Terms –––– The <dfn> Element :The <dfn> Element :The <dfn> Element :The <dfn> Element : The <dfn> element allows you to specify that you are introducing a special term. Its use is similar to the words that are in italics in the midst of paragraphs in this book when new key concepts are introduced. Typically, you would use the <dfn> element the first time you introduce a key term and only in that instance. Most recent browsers render the content of a <dfn> element in an italic font. <p>This tutorial teaches you how mark up yo<p>This tutorial teaches you how mark up yo<p>This tutorial teaches you how mark up yo<p>This tutorial teaches you how mark up your documents for the webur documents for the webur documents for the webur documents for the web using <dfn>XHTML</dfn>.</p>using <dfn>XHTML</dfn>.</p>using <dfn>XHTML</dfn>.</p>using <dfn>XHTML</dfn>.</p> This will produce following result: This tutorial teaches you how mark up your documents for the webThis tutorial teaches you how mark up your documents for the webThis tutorial teaches you how mark up your documents for the webThis tutorial teaches you how mark up your documents for the web usingusingusingusing XHTMLXHTMLXHTMLXHTML.... Quoting TextQuoting TextQuoting TextQuoting Text –––– The <blockquote> Element :The <blockquote> Element :The <blockquote> Element :The <blockquote> Element :
When you want to quote a passage from another source, you should use the <blockquote> element. Text inside a <blockquote> element is usually indented from the left and right edges of the surrounding text, and sometimes uses an italicized font. <p>The following description of XHTML is taken from the W<p>The following description of XHTML is taken from the W<p>The following description of XHTML is taken from the W<p>The following description of XHTML is taken from the W3C Web3C Web3C Web3C Web site:</p><blockquote> XHTML 1.0 is the W3C’s first Recommendation forsite:</p><blockquote> XHTML 1.0 is the W3C’s first Recommendation forsite:</p><blockquote> XHTML 1.0 is the W3C’s first Recommendation forsite:</p><blockquote> XHTML 1.0 is the W3C’s first Recommendation for XHTML, following on from earlier work on HTML 4.01, HTML 4.0, HTMLXHTML, following on from earlier work on HTML 4.01, HTML 4.0, HTMLXHTML, following on from earlier work on HTML 4.01, HTML 4.0, HTMLXHTML, following on from earlier work on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0. </blockquote>3.2 and HTML 2.0. </blockquote>3.2 and HTML 2.0. </blockquote>3.2 and HTML 2.0. </blockquote> This will produce following result: The following description of XHTML is takenThe following description of XHTML is takenThe following description of XHTML is takenThe following description of XHTML is taken from the W3C Web site:from the W3C Web site:from the W3C Web site:from the W3C Web site: XHTML 1.0 is the W3C’s first Recommendation for XHTML, following onXHTML 1.0 is the W3C’s first Recommendation for XHTML, following onXHTML 1.0 is the W3C’s first Recommendation for XHTML, following onXHTML 1.0 is the W3C’s first Recommendation for XHTML, following on from earlier work on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0.from earlier work on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0.from earlier work on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0.from earlier work on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0. You can use the cite attribute on the <blockquote> element to indicate the source of the quote. <p<p<p<p>The following description of XHTML is taken from the W3C Web>The following description of XHTML is taken from the W3C Web>The following description of XHTML is taken from the W3C Web>The following description of XHTML is taken from the W3C Web site:</p><blockquote cite=”http://www.w3.org/markup/”> XHTML 1.0 issite:</p><blockquote cite=”http://www.w3.org/markup/”> XHTML 1.0 issite:</p><blockquote cite=”http://www.w3.org/markup/”> XHTML 1.0 issite:</p><blockquote cite=”http://www.w3.org/markup/”> XHTML 1.0 is the W3C’s first Recommendation for XHTML, following on from earlierthe W3C’s first Recommendation for XHTML, following on from earlierthe W3C’s first Recommendation for XHTML, following on from earlierthe W3C’s first Recommendation for XHTML, following on from earlier work on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0. </blocwork on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0. </blocwork on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0. </blocwork on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0. </blockquote>kquote>kquote>kquote> Short QuotationsShort QuotationsShort QuotationsShort Quotations –––– The <q> Element :The <q> Element :The <q> Element :The <q> Element : The <q> element is intended to be used when you want to add a quote within a sentence rather than as an indented block on its own. <p>Amit<p>Amit<p>Amit<p>Amitaaaa is in Spain, <q>He is their at my home. I think I amis in Spain, <q>He is their at my home. I think I amis in Spain, <q>He is their at my home. I think I amis in Spain, <q>He is their at my home. I think I am wrong</q>.</p>wrong</q>.</p>wrong</q>.</p>wrong</q>.</p> This will produce following result: AmitAmitAmitAmitaaaa is in Spain,is in Spain,is in Spain,is in Spain, He is their at my home. I think I am wrong.He is their at my home. I think I am wrong.He is their at my home. I think I am wrong.He is their at my home. I think I am wrong. The <q> element can also carry the cite attribute. The value should be a URL pointing to the source of the quote. CitationsCitationsCitationsCitations –––– The <cite> Element :The <cite> Element :The <cite> Element :The <cite> Element :
If you are quoting a text, you can indicate the source placing it between an opening <cite> tag and closing </cite> tag As you would expect in a print publication, the content of the <cite> element is rendered in italicized text by default. <p>This HTML Tutorial<p>This HTML Tutorial<p>This HTML Tutorial<p>This HTML Tutorial is derived from <cite>World Wide Web Standardis derived from <cite>World Wide Web Standardis derived from <cite>World Wide Web Standardis derived from <cite>World Wide Web Standard for HTML</cite>.</p>for HTML</cite>.</p>for HTML</cite>.</p>for HTML</cite>.</p> This will produce following result: This HTML Tutorial is derived fromThis HTML Tutorial is derived fromThis HTML Tutorial is derived fromThis HTML Tutorial is derived from World Wide Web Standard for HTMLWorld Wide Web Standard for HTMLWorld Wide Web Standard for HTMLWorld Wide Web Standard for HTML.... Computer CodeComputer CodeComputer CodeComputer Code –––– The <code> Element :The <code> Element :The <code> Element :The <code> Element : Any code to appear on a Web page should be placed inside a <code> element. Usually the content of the <code> element is presented in a monospaced font, just like the code in most programming books. <h1> <code>This is inside code element</code></h1><h1> <code>This is inside code element</code></h1><h1> <code>This is inside code element</code></h1><h1> <code>This is inside code element</code></h1> This will produce following result: This isThis isThis isThis is inside code elementinside code elementinside code elementinside code element Keyboard TextKeyboard TextKeyboard TextKeyboard Text –––– The <kbd> Element :The <kbd> Element :The <kbd> Element :The <kbd> Element : When you are talking about computers, if you want to tell a reader to enter some text, you can use the <kbd> element to indicate what should be typed in, as in this example. The content of a <kbd> element is usually represented in a monospaced font rather like the content of the <code> element. <h1> <kbd>This is inside kbd element</kbd></h1><h1> <kbd>This is inside kbd element</kbd></h1><h1> <kbd>This is inside kbd element</kbd></h1><h1> <kbd>This is inside kbd element</kbd></h1> This will produce following result:
This is inside kbd elementThis is inside kbd elementThis is inside kbd elementThis is inside kbd element Programming VariablesProgramming VariablesProgramming VariablesProgramming Variables –––– The <var> Element :The <var> Element :The <var> Element :The <var> Element : This element is usually used in conjunction with the <pre> and <code> elements to indicate that the content of that element is a variable that can be supplied by a user. <p><code>document.write("<var>user<p><code>document.write("<var>user<p><code>document.write("<var>user<p><code>document.write("<var>user----name</var>")</code></p>name</var>")</code></p>name</var>")</code></p>name</var>")</code></p> This will produce following result: document.write(“document.write(“document.write(“document.write(“useruseruseruser----namenamenamename“)“)“)“) Program OutputProgram OutputProgram OutputProgram Output –––– The <samp> Element :The <samp> Element :The <samp> Element :The <samp> Element : The <samp> element indicates sample output from a program, script, or the like. Again, it is mainly used when documenting programming concepts. For example: <p>Result produced by<p>Result produced by<p>Result produced by<p>Result produced by the program is <samp>Hellothe program is <samp>Hellothe program is <samp>Hellothe program is <samp>Hello World</samp></p>World</samp></p>World</samp></p>World</samp></p> This will produce following result: Result produced by the program isResult produced by the program isResult produced by the program isResult produced by the program is HelloHelloHelloHello WorldWorldWorldWorld AddressesAddressesAddressesAddresses –––– The <address> Element :The <address> Element :The <address> Element :The <address> Element : The <address> element is used to contain any address. For example: <address>304, Menna<address>304, Menna<address>304, Menna<address>304, Menna Colony, HyderabadColony, HyderabadColony, HyderabadColony, Hyderabad –––– INDIA, 500032</address>INDIA, 500032</address>INDIA, 500032</address>INDIA, 500032</address> This will produce following result: 304, Menna Colony, Hyderabad304, Menna Colony, Hyderabad304, Menna Colony, Hyderabad304, Menna Colony, Hyderabad –––– INDIA, 500032INDIA, 500032INDIA, 500032INDIA, 500032 To Become more comfortable – Do Online Practice Block andBlock andBlock andBlock and Inline Elements:Inline Elements:Inline Elements:Inline Elements: We can categories all the elements into two sections:
• BlockBlockBlockBlock----level elementslevel elementslevel elementslevel elements – Block-level elements appear on the screen as if they have a carriage return or line break before and after them. For example the <p>, <h1>, <h2>, <h3>, <h4>, <h5>, <h6>, <ul>, <ol>, <dl>, <pre>, <hr />, <blockquote>, and <address> elements are all block level elements. They all start on their own new line, and anything that follows them appears on its own new line. • Inline elementsInline elementsInline elementsInline elements – Inline elements, on the other hand, can appear within sentences and do not have to appear on a new line of their own. The <b>, <i>, <u>, <em>, <strong>, <sup>, <sub>, <big>, <small>, <li>, <ins>, <del>, <code>, <cite>, <dfn>, <kbd>, and <var> elements are all inline elements. The elements which we have not discussed till now, will be discussed in subsequent chapters.
HTML HyperlinkHTML HyperlinkHTML HyperlinkHTML Hyperlink <a><a><a><a> The essence of an HTML document lies in the first two words: (H)yper(T)ext. In other words, it is the ability to link to other documents that makes HTML unique. How do HTML documents link to other documents? It does so via the <a> tag. The attributes for the <a> tag are href and name. Below we show an example for each: Example 1: Link to an external document. HTML: <a href="sample.html">This link</a> takes you to a document called "sample.html." Display: This link takes you to a document called "sample.html." Example 2: Link to an anchor within the same document. HTML: <a href="#atag">This link</a> takes you to a pre-determined location on the same page. Display: This link takes to a you to a pre-determined location on the same page. Note that you may also link to an anchor within an external document.
ImagesImagesImagesImages This lesson introduces how images and other graphical elements are incorporated into an HTML document, along with some basic image attributes. • Images - An Introduction o Image Source o Image Size • Image Attributes o Image Alignment o Image Alignment with Text o Alternate Text Images - An Introduction The <IMG> tag is used to incorporate graphics (typically icons or pictures) into an HTML document. Any image can be added to a web page, provided it is in GIF or JPEG file format. Also bear in mind that the larger an image's file size is, the longer it will take to download in a viewer's browser. "Image Source" and "Image Size" are the minimum attributes required for displaying an image. Image Source: The image source tag <SRC=> tells the browser where the image is physically stored so that it can retrieve and display it. It is important to remember that file names are case sensitive and must be typed correctly. Another important point to remember is that if an image is not stored in the same directory as the HTML documents, then the directory name must be included with the file name. Programmers commonly store images in a separate directory - often aptly titled "images". Thus an image source might appear written in HTML code as SRC="images/picture.gif". If an image is incorrectly named, missing or is listed in the wrong directory, a "broken graphic" icon will be displayed.
Image Size: Although not absolutely required, it is good practise to include HEIGHT and WIDTH information within the <IMG> tag. This speeds up the downloading process by allowing faster-loading text to load around areas where images will eventually appear. HEIGHT and WIDTH values are measured in pixels. Do not try to make the image smaller or larger by adjusting these attributes as you risk distorting the image by doing so. HTML Code Browser Display <IMG SRC="woman.gif" WIDTH=32 HEIGHT=32> Image Attributes Image Alignment: Use the LEFT, RIGHT or CENTER attributes within the <IMG> tag to align images relative to the browser window. See below for examples of how these attributes are used: HTML Code Browser Display <IMG SRC="woman.gif" WIDTH=32 HEIGHT=32 ALIGN=LEFT> <CENTER><IMG SRC="woman.gif" WIDTH=32 HEIGHT=32></CENTER>
<IMG SRC="woman.gif" WIDTH=32 HEIGHT=32 ALIGN=RIGHT> Image Alignment with Text: By default the bottom of an image is aligned with any text that follows, as shown below: HTML Code Browser Display <IMG SRC="hand.gif" WIDTH=108 HEIGHT=79>This hand is very big! This hand is very big! Vertical placement of text beside images can be altered from the bottom default setting by using the attributes ALIGN=TOP or ALIGN=CENTER, as shown below: HTML Code Browser Display <IMG SRC="hand.gif" WIDTH=108 HEIGHT=79 ALIGN=TOP>This hand is big! This hand is big! <IMG SRC="hand.gif" WIDTH=108 HEIGHT=79 This hand is
ALIGN=CENTER>This hand is big! big! Yet another option is to force text to appear under an image rather than beside it. For this effect, use the <BR CLEAR=ALL> tag to place a line break after an image, which will cause the text that follows to begin on the next line. HTML Code Browser Display <IMG SRC="hand.gif" WIDTH=108 HEIGHT=79 ALIGN=TOP><BR CLEAR=ALL>This hand is big! This hand is big! Alternate Text A good rule of thumb is to include alternate text that describes the image within an <IMG> tag. This is done for a number of reasons - 1. While the browser is still loading the viewer can still see the title or caption. 2. If the picture does not load, the viewer can still see the title or caption. 3. Users who choose to turn off image display in their browsers (a possible setting under the "preferences" menu), can still see the picture contents. To do this the "ALT" attribute is used. See below for an example of this attribute in use:
HTML Code Browser Display <IMG SRC="hand.gif" WIDTH=108 HEIGHT=79 ALT="Big Hand"> Try it out! In the box below, type the following HTML code, then click the "View" button. The HTML document you have written will be displayed in your browser. You may wish to change some of the tags and/or attributes to experiment with some of the different items discussed in this lesson. NOTE: If you would like to put one of the graphics from these lessons into your code, include the entire address. EG. http://www.alternetwebdesign.com/htmltutorial/imagename.gif Try typing this: <HTML> <HEAD> <TITLE>Images</TITLE> </HEAD> <BODY BGCOLOR="#FFFFFF" TEXT="#000000"> <IMG SRC="http://www.alternetwebdesign.com/htmltutorial/hand.gif" WIDTH=200 HEIGHT=146 ALIGN=TOP> </BODY>
</HTML> HTML ImageHTML ImageHTML ImageHTML Image <img><img><img><img> The <img> tag is used to embed an image on the HTML document. The attributes are as follows: • src: The file path to the image file. • width: The width of the image, in pixels. • height: The height of the image, in pixels. • alt: The text the browser will display when visitors mouse over the image. Search engines often places more weight on the text in the alt attribute. LinksLinksLinksLinks This lesson introduces the basics of using text and images as hyperlinks within and between HTML documents. • Hyperlinks - An Introduction • Text Hyperlinks • Relative Versus Absolute Pathnames • Image Hyperlinks • Image Borders • Image Maps • E-Mail Hyperlinks Hyperlinks - An Introduction
The chief power of the Web comes from its ability to link from one web page or site to any other regardless of where (ie. which computer server) they physically reside. This can be achieved by the use of hyperlink tags. Though only text could be so tagged in earlier versions of HTML (hence the origins of the name HyperTEXT Markup Language), today any text or image can serve as a hyperlink to any another page, site or even an e-mail address, jumping to the appropriate resource when clicked on. To add a link, the <A HREF=> and </A> tags are used. These tags bracket a portion of text or an image which will serve as a hyperlink, with the "HREF=" attribute identifying the destination URL. Text Hyperlinks To link with text simply bracket the desired word or phrase with the <A HREF=> and </A> tags. Typically, though not always, hyperlinked text is displayed in browsers with an underline, as illustrated below: HTML Code Browser Display <A HREF=http://www.google.com> Check out today's!</A> Check out today's! Relative Versus Absolute Pathnames An important point to remember when creating links is to make sure the correct URL is given. In order to provide a link to documents in other directories, the complete path from the current document to the linked document must be indicated. For example, a link to a file called "dilbert.html" located in the subdirectory "comics" would be written as: <A HREF="comics/dilbert.html">Dilbert Comic</A>
These are called relative links because the path to the file being linked to is specified relative to the location of the current file. The absolute pathname (ie., the complete URL) of the file could also be used, but relative links are more efficient in accessing a server. They also have the advantage of making documents more "portable" -- for instance, several web pages stored in a single folder on a local computer, with relative hyperlinks between each other, could be uploaded to a web server together, where the links would continue to work just as they do within a locally stored copy. The exception to this is when links are made to websites on other servers the absolute pathway must be given (ie., the complete URL). Thus the relative pathway for this page is: <A HREF="lesson5.htm"> Whereas the absolute pathway is: <A HREF="www.alternetwebdesign.com/htmltutorial/lesson5.htm"> Image Hyperlinks Instead of using text as hyperlinks, images may be used instead. This method of providing visual clues to links is becoming increasingly common on the Web. To do this, simply surround the image tag with hyperlink tags, in the same way a text link is tagged: HTML Code Browser Display <A HREF=http://www.unitedmedia.com/comics/dilbert/> <IMG SRC="dilbert.gif" WIDTH=78 HEIGHT=72 BORDER=0></A>
Image Maps Image mapping is a method of hypertext linking different parts of an image with the use of pixel coordinates to denote the areas. With an image map, a single image can provide many links to a number of different URLs. Below is a sample image map as it appears in HTML code and within a browser window: HTML Code Browser Display <MAP NAME="links"> <AREA HREF="lesson1.htm" SHAPE="RECT" COORDS="10,11,121,39"> <AREA HREF="lesson2.htm" SHAPE="RECT" COORDS="10,48,121,73"> <AREA HREF="lesson3.htm" SHAPE="RECT" COORDS="10,78,121,106"> <AREA HREF="lesson4.htm" SHAPE="RECT" COORDS="10,114,121,137"> <AREA HREF="lesson5.htm" SHAPE="RECT" COORDS="10,144,121,170"> <AREA HREF="lesson6.htm" SHAPE="RECT" COORDS="10,172,121,201"> <AREA HREF="lesson7.htm" SHAPE="RECT"
COORDS="10,205,121,235"> <AREA HREF="lesson8.htm" SHAPE="RECT" COORDS="10,234,121,266"> </MAP> <IMG SRC="lessons.gif" WIDTH="135" HEIGHT="278" usemap="#links" BORDER=0 NAME="links"> E-Mail Hyperlinks In order to create a link which launches the visitor's own e-mail program while filling in a specified address, include the "MAILTO:" tag with the desired e-mail address as shown here: HTML Code Browser Display <A HREF="MAILTO:name@server.com">Click here to send e-mail.</A> Click here to send e- mail. Try it out! In the box below, type the following HTML code, then click the "View" button. The HTML document you have written will be displayed in your browser. You may wish to change some of the tags and/or attributes to experiment with some of the different items discussed in this lesson.
NOTE: If you would like to put one of the graphics from these lessons into your code, include the entire address - ie. the Absolute Pathname. EG. http://www.alternetwebdesign.com/htmltutorial/imagename.gif Try typing this: <HTML> <HEAD> <TITLE>Want to learn more? </TITLE> </HEAD> <BODY BGCOLOR="#FFFFFF" TEXT="#000000"> Do you want to learn more? Click on the links below to get to some other useful HTML tutorials and reference documents: <UL> <LI><A HREF=http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimerAll.html>NCS A- A Beginners Guide to HTML</A> <LI> <A HREF=http://WWW.stars.com/Authoring/HTML/Intro/>The WDVL: Introduction to HTML</A> </UL> If you have any other HTML links you would recommend, please e-mail me at: <A HREF="MAILTO:info@alternetwebdesign.com">info@alternetwebdesign.com</A> <P> Click on the arrow to go to the next lesson.
Lesson 6 <A HREF="http://www.alternetwebdesign.com/htmltutorial/lesson6.htm"><IMG SRC="http://www.alternetwebdesign.com/htmltutorial/arrowright.gif" WIDTH=10 HEIGHT=8 BORDER=0></A> </BODY> </HTML>
TablesTablesTablesTables This lesson introduces the concept of tables as they are used in HTML documents. • Tables - An Introduction • Explanation of Table Tags • Explanation of Table Structure Tables - An Introduction Tables are used two ways in HTML: to display charts (what the designers of the <TABLE> tag originally intended it for); and as a means of controlling the layout of information on a web page. Although creating tables can be challenging, because readers of this tutorial will only be modifying information on existing web pages, all that is required is a basic understanding of the key elements and attributes which make up a table. Explanation of Table Tags <TABLE>...</TABLE> Encloses the table. The TABLE tag has the following variable attributes: "BORDER=" Specifies the thickness of the border around the table. When using a table to control a page's layout, the border is usually set to zero. "CELLPADDING=" Defines spacing within cells. "CELLSPACING=" Defines spacing between cells. "WIDTH=" Specifies the width of a table; typically
given as a percentage of the total browser window space available. <TR>...</TR> Specifies a table row within a table. You may define default attributes for the entire row. These are: "ALIGN=" (either LEFT, CENTER, or RIGHT) "VALIGN=" (either TOP, MIDDLE, or BOTTOM) "BGCOLOR=" Sets the background color of a table row (see Lesson 1 for more information on choosing colours). "WIDTH=" Specifies the width of a row; typically given as a percentage of the total space available. <TD>...</TD> Specifies a table data within the table row. The attributes for table data are: "ALIGN=" (either LEFT, CENTER, or RIGHT) "VALIGN=" (either TOP, MIDDLE, or BOTTOM) "BGCOLOR=" Sets the background color of the TABLE cell (see Lesson 1 for more information on choosing colours). "WIDTH=" Specifies the width of a table row. Typically given as a percentage of the available
space. Explanation of Table Structure Just as HTML documents have a basic structure, so too do tables: <TABLE> <TR> <TD>This is the table data cell #1</TD> <TD>This is the table data cell #2</TD> </TR> </TABLE> Below are samples of the various <TABLE> tags and their respective browser display: HTML Code Browser Display <TABLE BORDER=1 CELLPADDING=2 CELLSPACING=2> <TR> <TD>This is the table data cell #1</TD> <TD>This is the table data cell #2</TD> This is the table data cell #1 This is the table data cell #2
</TR> </TABLE> Two further notes about the creation of tables: Firstly, tables are often "nested" within each other as a means precisely controlling the layout of information on a page. Secondly, in order to make a table cell appear empty, some form of place holder must be inserted, be it the ASCII code for a blank space ( ) or perhaps a GIF consisting of a single pixel the same colour as the cell's background. Try it out! In the box below, type the following HTML code, then click the "View" button. The HTML document you have written will be displayed in your browser. You may wish to change some of the tags and/or attributes to experiment with some of the different items discussed in this lesson. Try typing this: <HTML> <HEAD> <TITLE>TABLE Manners</TITLE> </HEAD> <BODY BGCOLOR="#800080" TEXT="#FFFFFF"> TABLE Manners <TABLE WIDTH=80% BORDER=1 CELLPADDING=2 CELLSPACING=2> <TR> <TD>Rule # 1</TD>