The use of traps

It is not only in the opening that traps are dangerous. You can also tempt your opponent into a trap in the middlegame or endgame. 
The trap is also an important weapon in defense. Many players often make mistakes just before the end of the game, because their concentration flags and they do not take into account possible moves for their opponent. It is often worth fighting on in an apparently hopeless position. In any case, you should at that point try to set a trap for your opponent.

Of course you can also set traps in better or level positions. But the best option is to employ 'benign' traps, so as not to weaken your own position. In that way you do not take any unnecessary risks if your opponent discovers the trap in time and chooses a different route. Moreover such benign traps are harder to spot than a 'bad' trap, which often involves an unnatural-looking move, which therefore stands out. An experienced opponent will then quickly become suspicious!