In chess, a trick is a move designed to fool the opponent into making a mistake. In general, the trick move itself appears to be a blunder, often appearing to offer up a piece for free. However, taking the piece will be a mistake and will lead to a superior position for the player attempting the trick. A trick or series of tricks that successfully converts a lost position to a winning position is called a "swindle."
As a general rule, trick moves are not the best move in the position, and rely on the opponent falling for the trick in order to gain any advantage. A strong opponent will see through the trick and refuse to take the bait, leaving the player attempting the trick in an even worse position. Tricks are also often regarded as "cheap" and lacking in class and some players see tricks as being beneath their dignity.
Tricks are very rare at the highest levels of chess, because grandmasters rarely make blunders, so every apparent blunder will be carefully scrutinized in case it might be a trick. Accordingly, at high levels tricks are usually only played in "believable" situations, such as when both players are under time pressure, in blitz and rapid games with shorter time controls, or in a lost position, when a player has little left to lose and a swindle is the only hope for victory.