Outcome

Outcomes are the smallest pieces of a chance process, and an event is just a set of outcomes grouped together because you care about them. Rolling a fair six-sided die has six outcomes, 1 through 6, and the event roll an even number is made of the three outcomes 2, 4, and 6, so its probability is $3/6 = 0.5$. The probabilities of all the outcomes in a sample space always add to 1. Outcomes do not have to be equally likely, even though the die example happens to be.