A pitch delivered by the pitcher to the batter is a strike when the pitcher succeeds in legally preventing the batter from hitting a fair ball. I pitch is defined as a strike when any of the following occurs:
- The pitcher throws a pitch in the strike zone, which the batter does not swing at.
- The batter swings at the pitch and completely misses (whether the pitch was in the strike zone or not)
- The batter swings at the pitch and hits a foul ball, unless the batter already has two strikes against him, in which case the pitch is a "nothing" -- neither a strike nor a ball.
- The batter swings and hits a foul tip, which is caught by the catcher. (If not caught by the catcher, it is a foul ball.)
- The batter bunts and hits a foul ball.
A strikeout occurs when the batter accumulates three strikes. Usually, on a strikeout, the batter is out. However, there is a situation where the batter might not be out; see dropped third strike.