In baseball or softball, a strikeout occurs when a batter accumulates three strikes during a time at bat. It means the batter is out, unless the third strike is not caught by the catcher and the batter reaches first base safely as a result. A strikeout is a statistic recorded for both pitchers and batters, and is usually denoted by the letter K, or sometimes by the initialism SO. A "strikeout looking"—in which the batter does not swing and the third strike is called by the umpire—may be denoted by an inverted K.