As Denzel Washington confidently says in the movie Philadelphia, can someone please explain this rule to me as if I'm a 6 year old?

Many thanks :)

Infield fly rule is called when there are at least two runners on base that would both be a force out, i.e. 1st and 2nd base is occupied or bases are loaded. Infield fly ruled is called only on a popup to the infield so the infielder doesn't let the ball drop on purpose and then immediately throw the ball to third and then to second to get to force outs for a double play. It is done to protect the team at bat.

After reading that simple explanation, it all makes perfect sense now. You wonder why they never let that pop fly drop just to double up the players and there's the reason why.

Many thanks!

Two notes:

1. There must be at least 2 runners on base, and it must be a force situation, so runners must be on 1st and 2nd, or 1st, 2nd & 3rd.

2. The ball remains live and the runners are free to advance at their own risk. When my daughter was playing softball in the town league at the age of 11 it was hilarious to see the infield fly rule in operation. Typical play: the batter pops the ball up, the ump yells "Infield fly, the batter is out," the girls on base have no idea what that means and run anyway, the infielders aren't so good so they don't catch the pop up, and the runners are all safe at the next base. This inevitably leads to arguments among the parents and/or coaches who think the runners ought to be sent back to their original base. But of course they shouldn't, because the defending team had the chance to throw out one or both runners. In one game I remember seeing two runs score on an infield fly!