In poker, "muck" refers to the discard pile into which players may throw their folded hands, and into which the dealer places burned cards). It also refers to when a player is folding their hand (face down) without saying anything. In fact, the hand is not folded until it reaches the muck (it can be taken back and used if the dealer did not take the hand yet) ). The practice of mucking cards when discarding helps to ensure that no other player can reliably determine which cards were in the folded hand).

If a player has not folded, they can have their hand "mucked" if another player attempts to discard but one or more cards end up in the live players hand). To prevent this, many players will place a chip or other object on their cards, which helps to prevent errant cards from entering their hand. Sometimes they are referred to as card covers, card guards, or card protectors).

In some variations of poker, a player may "muck" their cards in order to reinforce a bluff while preserving their image on the table). However, mucking or hand mucking may also refer to a form of sleight of hand, and, if used in a card game, is considered cheating).

If a player mucks their hand, they forfeit it and it is considered dead. In some cases, other players may request to see a mucked hand, but this depends on the casino rules and the type of game being played.