If you've ever seen a trick shot exhibition or tournament, you've undoubtedly witnessed the performer hitting one pool ball on top of another. We call this tapping the balls. What it does is create a little divot in the pool table felt for the ball to rest in. As a trick shot artist, this is an important skill to learn to do correctly, and it can help you out in a number of ways.
Whenever I do a show, inevitably, someone in the audience always asks why I need to tap the balls. The main reason is so that the pool ball stays exactly where I want it. It's not half an inch to one side or the other.
Older, well-worn tables have divots or other irregularities in the pool table cloth already. This can make setting up a trick shot difficult as the balls will tend to roll one way or another. By creating new divots, the balls end up where I need them to be.
This is particularly important for artistic setup shots where a number of balls are set up in a cluster. These shots typically don't work if there are gaps between the balls. By tapping the balls in place, I can ensure that these balls are in the right place and that they are all touching. There are shots where the gap between balls needs to be precise as well, and tapping helps with that.
If the balls are tapped in well, you can usually find these divots again. When I'm doing exhibitions, I'll usually try to show up early to a venue and tap in a number of shots beforehand. During the exhibition, this makes setup of the shots faster and easier as they seem to just roll in to place. It also makes trick shots look effortless, but the audience didn't see the work I put in beforehand.
When I'm practicing, tapping the balls is helpful so I can set up the shot again in the exact same way. I can try different spins and speeds or other adjustments and see what effect they have on the shot. On the flip side, if I tap the balls in and miss, I can also set it up again and, if I know one of the balls missed to the left of the pocket, I can adjust it slightly to the right and make a new divot. It's certainly possible to have too many divots in a certain area which can get confusing.
In tournaments, if I'm shooting a shot someone else has made, sometimes I can find their divots. Then I usually don't have to worry about if my setup is correct. It's tougher if I'm the first guy up. In a head-to-head match, the other option is to make as many divots as possible so my opponent doesn't know which one I've used. Sometimes it's worth it, sometimes it's not. It depends how difficult the shot is otherwise.