Hole carding is the practice of counting cards and showing them to the player before any other action is taken. Hole carding can be used to improve your chances of winning at blackjack, but it is also illegal in most jurisdictions.
Hole carding is most commonly used in European-style blackjack, where the dealer deals each player two cards face down and then hits on a hand. The player can either hit or stand. If the player hits, they may choose to show their hole card (the fourth card in their hand) to the dealer before making their decision.
Showing the hole card allows the dealer to double down on any hands that are already close (for example, if a player has a two and a three, they may choose to show their hole card and take another two cards, for a total of five cards). If the player stands, they may keep their original two cards and still hit if they get an Ace or a ten.
Hole carding has been banned by many jurisdictions due to its use as an edge play. While it is possible to win at blackjack without ever showing your hole card, showing your hole card increases your chances of winning by giving the dealer an extra opportunity to count against you.
