In statistics and probability, the term describes events that cannot occur simultaneously. Two events are considered to be this way if they have no outcomes in common. For example, when a fair coin is tossed, the outcome can either be heads or tails. These two outcomes cannot happen at the same time; therefore, they meet the condition. Similarly, selecting a red card and a black card from a standard deck in a single draw are events that preclude each other.
The concept is fundamental to calculating probabilities, especially in scenarios involving mutually exclusive possibilities. Understanding it allows for accurate computation of the likelihood of various outcomes by ensuring that no overlap is counted. Historically, its formalization has been critical in developing robust probability models and inferential methods that rely on accurate assessment of potential events. It forms the basis of many probability rules, making statistical analysis and decision-making more precise.