Fair ball

In

first base. By contrast, a foul ball

is a batted ball that does not entitle the batter to attempt to reach first base. Whether a batted ball is fair or foul is determined by the location of the ball at the appropriate reference point, as follows:

if the ball leaves the playing field without touching anything, the point where the ball leaves the field;
otherwise, if the ball first lands past first or
third base
without touching anything, the point where the ball lands;
otherwise, if the ball rolls or bounces past first or third base without touching anything other than the ground, the point where the ball passes the base;
otherwise, if the ball touches anything other than the ground (such as an umpire, a player, or any equipment left on the field) before any of the above happens, the point of such touching;
otherwise, (the ball comes to a rest before reaching first or third base), the point where the ball comes to a rest.

If any part of the ball is on or above fair territory at the appropriate reference point, it is fair; otherwise, it is foul. Fair territory or fair ground is defined as the area of the

foul poles.^[1]

However, certain exceptions exist:

A ball that touches first, second, or third base is always fair.

Under Rule 5.09(a)(7)-(8), if a batted ball touches the batter or his bat while the batter is in the batter's box and not intentionally interfering with the course of the ball, the ball is foul.

A ball that hits the foul pole without first having touched anything else off the bat is fair.