event

An event is something that occurs at a particular time and place and may be of interest due to its significance, rarity, or impact. In everyday language, events include gatherings such as meetings, parties, sports games, concerts, and ceremonies; planners coordinate venues, dates, invitations, and services.

In event management, an event is a planned activity with objectives, logistics, budgets, and stakeholders, often requiring permits, risk management, and evaluation.

In natural and social contexts, events can be accidental or natural: weather events (storms, floods), geological events (earthquakes), or political or cultural events (elections, protests, festivals).

In science, an event can be a specific happening within a system, such as a chemical reaction occurring at a certain time or a particle decay observed in an experiment.

In probability theory, an event is a set of outcomes from a random experiment; events are subsets of a sample space and are assigned probabilities by a probability measure. Notation uses brackets or letters like A, B, etc. Conditional probability, independence, and joint events are common topics.

In computing and software design, events are signals that indicate something has happened, prompting event handlers to execute, enabling event-driven programming and user interfaces.

Common to many uses is the idea of time and occurrence: an event is something observed or planned, distinct from ongoing processes, and often analyzed by its causes, effects, and context.