If, (while the infield fly rule is in effect), the ball is caught, the runners must tag up. If the ball is dropped or falls to the ground untouched, the runners may advance at their own risk.
Clarification:
The infield fly rule was enacted to prevent teams from getting an easy double or triple play by letting a popup in the infield drop. An infield fly is just like any other fly ball, with the exception that the batter is immediately out, with results in the runners not being required to advance in the even that the ball is not caught
Any umpire may indicate the infield fly rule is in effect by yelling "Infield Fly" and extending his right hand above his head and pointing. However, the infield fly rule is in effect whether or not any umpire does this.
no because the infield fly rule is if a ball is hit in the air for something like 5seconds then it is automttically an out
If the infielder is under the ball making it look like they are then yes there is an infield fly rule.
Infield fly rule
Any fielder is allowed to catch any fly ball he can. If you are referring to the infield fly rule: under this rule, the hitter is called out and play continues as if the fly were caught even if no one catches it. It does not matter who catches it, but if the ball drops, the runner can tag up and run at his risk. The rule is only called when the ball seems certain to be catchable. The purpose of the rule is to prevent an infielder from intentionally dropping pop-up in order to get a double play.
any umpire can
As soon as the ump calls the infield fly rule, the batter is out, but the runners can still advance at their own risk. To answer your question specifically, no, the fielder can't do that - that is the exact result that the infield fly rule was enacted to prevent! Usually when they call the infield fly rule, the baserunners go back to the bases relatively quickly, because the play is over.
No, as long as it is a fair ball. Once the umpire signals the infield fly rule the batter is automatically out. However, if the ball is dropped and is ruled a foul ball, the umpire reverses his call and the batter continues his turn at bat. Nevertheless, the batter can not reach first from that batted ball. You will often find an umpire state "Infield fly, Batter is out if Fair". When the rule is in effect, the batter may not get on first base.
Infield fly rule.
Yes, they do have to tag up, unless the fielder, for whatever reason, does not catch the ball.
No the HR tag does not need a close tag.
The infield fly rule came into existence in 1895. However, the rule stated that it was only in effect when there was one out. This was changed in 1901 to include being in effect when there were no outs as well as when there was one out.