What is the rule of multiplication

The rule of multiplication applies to the following situation. We have two events from the same sample space, and we want to know the probability that both events occur.

Rule of Multiplication If events A and B come from the same sample space, the probability that both A and B occur is equal to the probability the event A occurs times the probability that B occurs, given that A has occurred.

P (A ∩ B) = P (A) P (B|A)