This document provides an overview of key concepts in probability. It defines probability as a measure of likelihood between 0 and 1, and discusses how probability is used in various fields. Key terms are explained, such as randomness, trial, independent trial, experiment, event, and sample space. Randomness refers to experiments with unpredictable outcomes, like rolling a die. Trials are the individual occurrences of an experiment, like each coin toss. The document also discusses empirical probability, which is the probability of an event calculated based on the frequency of outcomes from experiments. Empirical probability depends on the specific experiment and can take on different values.