One of the trickier elements in playing poker is getting the maximum value out of a hand. While some poker advice will have you going aggressive to the max each and every time you draw two aces or something similar as a starting hand, you can often scare off potential money. The art of the trap, sometimes called the "slow roll" or the "slow play," can sometimes be a bit of a risk but will almost always bring more money per hand.
A good example of a trap would be starting with a high pocket pair, such as pocket Kings, and simply calling or checking pre flop rather than raising. This is especially effective if you are early in position. Raising from early in position is a good way to have those behind you fold their draw cards rather than calling the minimum. Of course if you are in the big blind position and you have a lot of players who have called the minimum then a minimum raise would not be a bad idea, as most of those players would feel compelled to call.
After the flop comes and as long as something dangerous did not appear, such as an ace, then you could continue trapping. Late position is good here, especially if other players are betting, in which case you would just call. From early position you would need to check. You may want to check raise if someone after you checked, which would end your trapping efforts. If you still feel you have the best hand, just call.
Trapping gives you the opportunity to let other players gamble on draws or sub best hands. In the end this means more money in your stack. Not to mention a healthy respect from the other players about your poker skills.