When some no-limit hold'em players think of "trapping" they immediately think of "slow playing." In fact, some will equate the two, mistakenly believing the only way to trap an opponent after the flop is by slow playing.
Trapping actually refers to a broader postflop strategy that can but doesn't necessarily involve slow playing. You can "trap" and still play a hand "fast" by betting and raising right away for value.
Trapping by Slow Playing
We're all familiar with slow playing, a strategy that can work especially well in certain situations, particularly against aggressive opponents.