Different Serves! Learning with "THE BEASTS"
Differences between the Slice, Flat and the Tennis Kick Serve
A slice serve bounces low and bends to the right side of the returner. For left-handers, the directions are all reversed. Therefore, if you want to improve your serve and have a very reliable second serve, you will need to learn how to hit a kick serve, a twist serve and a slice serve, to go along with your basic flat serve.
For many players, the flat serve is their bread-and-butter first serve. For many left-handed players, it is the slice serve, because this goes wide to the right-handed receiver’s backhand. However, there have been players in the history of the sport who have specialized in how to hit a kick serve. These players include Stefan Edberg and Patrick Rafter, both former top-ranked players and two-time US Open champions.
The US Open is played on fast hard courts and both of these men are serve-and-volley players. The ball bounces high and fast so kick serves are very much useful for setting up a quick dash to the net. The spin makes the ball travel slower through the air, giving them more time to close in to the net.
Work cited: http://www.optimumtennis.net/how-to-hit-a-kick-serve.htm