Mutually exclusive events are events that cannot occur at the same time. If one event happens, the other cannot. Mathematically, for events A and B:
P(A ∩ B) = 0.

Exhaustive events are a set of events that cover all possible outcomes of an experiment. This means at least one of the events must occur.

Example: In tossing a coin, events A = "heads" and B = "tails" are mutually exclusive (can’t happen together) and exhaustive (one must happen).

If events are both mutually exclusive and exhaustive, their total probability sums to 1:
P(A) + P(B) = 1.