Hole Carding

Hole carding refers to obtaining knowledge of cards that are supposed to be hidden from view in card games. The term is usually applied to blackjack but can apply to other games with hidden hole cards, like three card poker and Caribbean stud poker. So long as it does not involve the use of a device like a mirror or actions like touching the dealer's cards, in most jurisdictions hole carding is a legal form of advantage gambling in casino table games. In other games, like stud poker, casinos normally have rules against rubbernecking or having a confederate stand behind an opponent to signal hole cards.

Blackjack players must usually make playing decisions based on only seeing one of the dealer's cards (the upcard). But if the dealer's hole card is spotted, a player who plays correctly has a theoretical advantage of up to 13% instead of the normal player disadvantage of around 0.5%. A hole-card player will often choose not to make certain plays, such as hitting a hard 19 against a dealer 20, so as not to reveal that he can see the dealer's hole card.

Dealers can thwart this strategy by turning their first card face-up and not dealing their second until the players have all played.