The Common Language Runtime (CLR) is the virtual machine component of Microsoft's .NET framework that manages the execution of .NET programs. It provides services like memory management, type safety, exception handling, garbage collection, security, and thread management. The CLR converts compiled code into machine instructions using just-in-time compilation. All .NET framework programs, regardless of programming language, are executed by the CLR. There are four main components of the .NET Framework: the CLR, Common Type System (CTS), Base Class Library (BCL), and Common Language Specification (CLS).