Fair ball

In baseball, a fair ball is a batted ball that entitles the batter to attempt to reach first base. In order for a batted ball to be fair, it must be hit in such a way that it:^[1]

• settles on fair ground between home and first base, or between home and third base; or
• is on or over fair territory when bounding past first or third base; or
• touches first, second, or third base (which by rule are in fair territory); or
• touches the person of an umpire or player while the ball is on or over fair territory (unless it touches the batter in the batter's box, or bounces off the ground and immediately hits the bat); or
• passes out of the playing field in flight while over fair territory, or touches any part of the foul pole, including any attached screen, while in flight; or
• strikes any object for which the specific ballpark's ground rules specify that a batted ball striking that object is a fair ball (e.g., a roof if present); or
• lands for the first time in fair territory in the outfield.

Fair territory or fair ground is defined as the area of the playing field between the two foul lines, and includes the foul lines themselves and the foul poles.

On a fair ball, the batter attempts to reach first base or any subsequent base, runners attempt to advance and fielders try to record outs. A fair ball is considered a live ball until the ball becomes dead by leaving the field or any other method.

By contrast, a foul ball is a batted ball that does not entitle the batter to attempt to reach first base.

References

1. Rule 2.00. Definition of terms (PDF), Major League Baseball, retrieved 2009-06-13