Trap

A maneuver that looks at first glance like it hands the other side an advantage, but really lures the opponent into a bad position. Here, for example, are two opening traps:

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1. 1.
2. 2.
3. 3.
4. 4.
5. 5.
6. 6.
8. 7.
9. And Black suffers material losses

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1. 1.
2. 2.
3. 3.
4. 4.
5. 5.
6. 6.
7. 7.
8. And White is left down a piece

Playing for a trap

There is, however, an important difference between these two traps. In the first case, had Black played 6...♕f6 instead of 6...♘e5, White's whole play for the trap would have failed, and White would have had to settle for a worse position. In the second case, Black was simply developing steadily and set the trap along the way.

Hence the conclusion: do not play for a trap if correct replies by the opponent can leave you worse off; set a trap when it costs you nothing even if the opponent sees through it, or when your position is already so bad that only a trap can save you.