The infield fly rule in baseball is a rule designed to protect baserunners from being unfairly forced out on a routine, easy-to-catch fly ball in the infield. Here are the main points of the infield fly rule:

• It applies when there are less than two outs.
• There must be runners on first and second, or bases loaded (first, second, and third).
• The batter hits a fair fly ball (not a line drive or bunt) that an infielder can catch with ordinary effort.
• When the umpire judges the fly ball meets these conditions, they call "infield fly," and the batter is automatically out regardless of whether the ball is caught.
• The runners on base are no longer forced to advance because the force play is removed.
• Runners may advance at their own risk after the ball is caught or if it drops.
• The intent is to prevent the defense from intentionally dropping the ball to create an easy double or triple play.
• The rule does not apply to line drives or bunts.

The umpire typically signals by raising a hand and announcing the call to alert players and coaches. If the ball is caught, runners must tag up before advancing; if not caught, runners are not required to tag up but can advance at their own risk. The rule was established to ensure fair play and prevent defensive teams from exploiting a loophole by letting pop-ups drop in the infield intentionally to get multiple outs easily.