The measure of the likelihood of an event happening is called probability. Probability quantifies uncertainty and ranges from 0 to 1, where 0 indicates that an event cannot occur, and 1 denotes certainty that the event will happen. It is often expressed as a fraction, decimal, or percentage. In practical terms, probability helps in various fields, including statistics, finance, science, and everyday decision-making, to assess risks and outcomes. Probability theory enables us to predict and understand patterns in random phenomena.