Shutouts are recorded when a pitcher pitches a complete game without allowing a run to be scored against.
Also referred to as "SHO."
More about Shutouts Leaders
Pitching shutouts are becoming rarer as of late, and they are now quite a feat when they take place. A shutout is credited to a starting pitcher if he starts and finishes a game and the opposing team doesn’t score any runs. Thus a pitcher can get credited with a shutout if pitches just five innings in a rain-shortened game, but he can also not be credited with a shutout if he leaves the game after nine innings in a 0-0 tie. Given how much more closely teams watch pitch counts now than in the past and the understanding of a pitcher’s decreasing effectiveness in the late innings, managers rarely give their starting pitchers an opportunity to finish a game.