Blackjack (sometimes called Twenty-one, or in French Vingt-et-un) is probably the most widely played casino game in the world. Much of its popularity is due to the simple rules as well as the combination of chance and skill required by the player, who tries to calculate the probability of drawing certain cards based on the ratio of high to low cards in the deck.

The objective is to beat the dealer's hand by drawing cards that combine to total 21, or as close to this number as possible. If a total of 21 points is exceeded then the hand is "bust", meaning that the player loses. If the dealer's hand (i.e. playing for the house) goes bust then all hands remaining in the game with 21 or less are paid out.