Event (probability theory)

In probability theory, an event is a set of outcomes (a subset of the sample space) to which a probability is assigned.

Mathematically, an event is defined as an element of the σ-algebra of the probability space.

For example, if we assemble a deck of 52 playing cards and two jokers, each individual card represents an elementary event in a 54-element sample set, but subsets of the sample set (regardless of how many elementary events they contain) are called simply "events". Events from this sample set include "King" (a set 4 elementary events), "Spade" (13 elementary events), and "Face card" (12 elementary events).