Trade outs for runs with sacrifice plays

There are two types of sacrifice play, wherein a batter accepts an out for the sake of moving a runner on second or third base closer to home so he or she can score a run. A sacrifice bunt is a special type of play where the batter uses the bat to bump the ball from the air without sending it forward. The ball lands just in front of home plate, making it a simple matter for the catcher to retrieve the ball and ground out the batter; however, in the time it takes to do this, another runner may be able to advance to third base or even home plate.
The very fastest runners can sometimes survive a bunt and make it to first without getting grounded out.
A sacrifice fly is a pop fly (a high, arcing ball thats very easy to catch) that gives a third baseman time to run home before the runner gets a flyout.