In trick-taking games, to ruff means to play a trump card to a trick (other than when trumps were led). According to the rules of most games, a player must have no cards left in the suit led in order to ruff. Since the other players are constrained to follow suit if they can, even a low trump can win a trick. In some games, like Pinochle and Preferans, the player who cannot follow suit is required to ruff. In others, like Bridge and Whist, he may instead discard (play any card in any other suit). Normally, ruffing will win a trick. But it is also possible that a subsequent player will overruff (play a higher trump). Historically, ruff meant to "rob" i.e. exchange a card with the stock.