Balk

In baseball, a pitcher may commit a number of illegal motions or actions which constitute a balk. If a balk occurs, the current play is allowed to continue. If each baserunner advances one base safely, the infraction is ignored. Otherwise, the balk is called "no pitch" and each runner is awarded one base (in contrast to a walk, in which runners only advance if forced).

There are two motivations behind the balk rule. A pitcher is constrained to a certain set of motions prior to and during a pitch; if these are violated, a procedural balk will be called (see also pitching positions). Pitcher's actions that illegally deceive baserunners are called punitive balks.