One of the enjoyable aspects of baseball is its uncertainty. At the beginning of the season, it is difficult to predict the number of games won for particular teams and the playoffs typically include “weak” teams and exclude “strong” teams. The outcome of a single baseball game is uncertain although the outcome becomes more certain as the game progresses and runs are scored by the two teams. Probability is a way of measuring uncertainty and graphs are used to illustrate various probabilities in this chapter.