This document defines probability and provides examples of calculating probability through experiments involving coin tossing and dice rolling. It states that probability is a measure between 0 and 1 of the likelihood of an event occurring, with 0 being impossible and 1 being certain. The basic probability formula is defined as the number of favorable outcomes divided by the total number of possible outcomes. Experiments are defined as procedures that can be repeated with a set of possible outcomes, with each repetition being a trial. The probability of an event is calculated by taking the number of outcomes where the event occurs and dividing by the total number of outcomes.