Section 5: Rules of Play
Putting the ball in play: Each half-inning begins with the pitcher delivering the ball to the batter from a legal pitching position — the windup position or the set position (Rule 5.07). A pitch delivered while not in a legal pitching position, or an illegal motion by the pitcher with runners on base, is a balk (Rule 6.02), which advances all base runners one base.
Balls and strikes (Rule 5.05, 5.09): A pitch outside the strike zone that the batter does not swing at is called a ball; four balls award the batter first base (base on balls). A pitch in the strike zone, or any pitch at which the batter swings and misses, or any foul ball with fewer than two strikes, is a strike; three strikes constitute a strikeout, which is an out.
Fair and foul balls: A batted ball that settles on or is touched while over fair territory (between the foul lines) is a fair ball and remains live for play; a ball that settles in foul territory, or is touched there, is a foul ball, generally counted as a strike (unless it would be the third strike, in which case the batter is not out except on a foul tip or bunt attempt).
Advancing and putting out runners: A batter becomes a runner upon a fair-batted ball, a base on balls, being hit by a pitch, or catcher's interference. Runners may advance at their own risk on batted balls, wild pitches, passed balls, or when forced by a following batter-runner. A runner is out if tagged with the ball while off base, forced out at a base ahead of a batted ground ball, or caught off base on an appeal or pickoff.
WBSC Special Playing Regulations: International WBSC tournament competitions apply supplementary regulations not found in domestic amateur or professional codes, including a mercy rule that ends the game early when one team leads by a specified margin (commonly ten runs) after seven innings, and a tiebreaker procedure in extra innings that places a runner on second base to start each half-inning until the tie is broken (WBSC Official Rules of Baseball 2025-2026, Special Playing Rules).