Probability/Elementary event

The sample space in any discussion of probabilities is a set of elementary events, which are the individual irreducible occurrences that make up the set of all possible occurrences. For example, the elementary events that make up the sample set of tossing a die are the numbers 1 though 6. 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. Subsets of the sample set (regardless of how many elementary events they may contain) are called simply events. Events from this sample set include "King" (4 elementary events), "Spade" (13 elementary events), and "Face card" (12 elementary events).

This discussion refers to finite sample spaces. Advanced courses in probability theory consider sample spaces in which not every point is an event to which a probability can be assigned.