Stolen base

In baseball, a stolen base occurs when a runner advances to a base unaided by other actions and the official scorer rules that the advance should be credited to the action of the runner. The umpires determine whether the runner is safe or out at the next base, but the official scorer rules on the question of credit or blame for the advance under Rule 10 (Rules of Scoring) of the MLB's Official Rules.^[1]

A stolen base most often occurs when a base runner advances to the next base while the pitcher is pitching the ball to home plate.

Successful base stealers must be fast and have good timing.