The set of all possible outcomes of an experiment is called the sample space. For example, the sample space of flipping a coin is either heads, $H,$ or tails, $T.$

Here, the sample space is shown in a tree diagram. Each row represents the possible outcomes. If the coin is flipped another time, the tree diagram will get another row with the possible outcomes.

Thus, the probability of two specific outcomes can be determined. For example, whats the probability that the result of both flips are heads?