Probability of Events

Any subset of a sample space is called an event. If an event has one element only it is then called a simple event. This is the formal definition of the word "event" we use in the theory of probability; it is different from what we mean by this word in everyday language.

To understand the concept of an "event" in the context of probability, let us try an example. Assume that two dice are rolled together. Then the sample space, S, of this experiment is as follows: