as we get started with the baseball and softball seasons  were going to have this question come up again I was at a game the other day for my grandson, but it doesn't make any difference whether it's peewee baseball or major-league the rules are exactly the same.  There are three or four cases that come up every year that coaches, parents, and players don't know what makes a ball fair, what makes a ball foul.

So I'm going to break them down in the simplest of terms: 

1. the first and foremost decision to be made on whether a ball is  fair or foul is where is the ball located when it is touched by a player. with a player touches it  it is where the ball is located that makes it fair or foul, where the player is located makes no difference at all. The most common is that a player at third or first is still it fair territory reaches across the foul line to field the ball and touches the ball while it's over foul territory that makes it foul.

2. A ball that hits off of home plate is neither fair nor file until somebody touches it.

3. the one that seems a little contrary is the one that where the ball hits in fair territory and then lands in foul territory and the umpire calls it fair.  Here's the reason why  a ball that hits in front of first or third in fair territory then passes over  first or third  or inside first or third then lands in foul territory is a fair ball because it passed over first or third after it hit the ground in front of those two bases. If it  lands  for the first time passed first or third in where it lands is determined  fair fell.

4. The line is considered in fair territory, if it just touches any part of the line that is a fair ball.

5. One extremely rare situation, I've only seen it twice in 50 years of umpiring but it's there so I say it if a ball hits the pitching rubber and then rebounds into foul territory before it is touched by a player then it is  a foul ball, because it never passed first or third.

One last case for you to think about that you seen all the time it really illustrates what I've said above that a player is underneath a pop-up, to the infield, they miss it completely and it lands on the ground and you hear the coaches say let it go foul, let it go foul because they want the ball to land and be touched in foul territory.. Or the reverse of it a ball is rolling down the line from a queue shot and the coaches tell the players  touch it touch it in foul territory so that is  ruled a foul ball.

Where the ball is been touched that's what makes it fair or foul in front of the bases,, behind first or third it's where it lands.

Arnald Swift umpire 50 years plus (at all levels)  coaching 40 years plus