The numbers three and four appear prominently in the game of baseball. There are three strikes for an out, three outs per half-inning (i.e., teams switch after three
outs, where each first half-inning is called the "top" and the second the
"bottom"),
innings in a game, giving
outs per game (assuming no extra innings). In addition, there are
players per team. Four balls are needed for a walk.
There are
games in the regular season,
each for home and away games.
The number of bases can either be regarded as three (excluding home plate) or four (including it).