Blackjack is a card game in which players compete against the dealer. The goal is to have a higher total value than the dealer without going over 21. The game may also be played with more than one player per table, with each having an independent hand against the dealer. If a player busts, they lose. If the dealer also busts, the hand is a push and neither wins or loses.
The number of cards dealt and the rules of play vary between casinos and games. Most modern games use six to eight decks, with the dealer shuffles the cards before dealing each hand. Some games are dealt face-down, while others are dealt in a shoe (a boxlike device that holds the cards). Typically, each player has a betting box that is placed on the left of the table. A player may choose to bet any amount, including no bet at all.
When a player receives his or her two cards, they must decide whether to hit, stand, split, or double down. A hit results in an additional card being added to the current hand; a stand results in the player keeping the current hand, not receiving any further cards; and splitting and doubling allow the player to create two hands that are played independently of each other. Doubling down is usually only permitted when the current hand has a value of 11 or more; however, some games permit doubling down even on hands with a value of 10 or less.
Some games of blackjack offer the option of taking insurance bets. These bets are placed against the dealer and pay out if the dealer has a blackjack, or a hand that is a close approximation of a blackjack (an ace and a 10 or face card). This type of bet is generally not considered a good long-term investment for the player, as it pays out less than one-third of the time.
The house edge for blackjack is often estimated as 0.5 percent or less, making it one of the lowest-edge casino games. Despite this, players should note that if they do not follow basic strategy, their odds of winning are very slim.
Blackjack is often played in tournament form, with a set number of chips awarded to each competitor at the end of a round. Some tournaments are structured as elimination events, with the lowest-stacked player dropped after a predetermined number of deals. Other tournaments are run in a round-robin format, with each player playing against all other players at the same table. This format is most common in charity events and private circles.