The penalty for a balk in baseball is an automatic ball for the batter. A balk can occur in several ways.
The umpire can call a balk if the pitcher touches the rubber and fakes a throw to first base. It can also occur if the pitcher throws to a base without stepping towards that base. Other types of balk include when a pitcher throws to a base that is not occupied by a runner or if the pitcher throws the ball to the batter without looking at him. On average, there must be at least one runner on base before it is considered a balk.