Blackjack, also known as vingt-et-un, twenty-one 21 and pontoon, is one of the most popular casino card games in the world.
Much of its popularity is due to the mix of chance with elements of skill and decision making, and the publicity that surrounds the practice of card counting, in which players can turn the odds of the game in their favor by making betting and strategy decisions based on the cards that have been dealt.
Casinos strongly frown upon card counting, but it is a difficult skill to master and few players are successful at it.
In blackjack, the players bet against the house dealer rather than against each other.
The goal of each player is to have a higher point total than the dealer without going over 21.
The values of the cards in each hand are added with 2 through 10 having face value, Ace having value 1 or 11 (player's choice), and King, Jack, and Queen cards having the value 10.
If the player's and the dealer's hands have the same point value, this is known as a "push", and neither player wins the hand.
After initial bets are placed, the dealer deals the cards (either from a single hand-held deck of cards, or more commonly from a shoe containing four or more decks): two cards to each player, including himself.
One of the dealer's two cards is visible, the other hidden (the hidden card is known as the "hole card"; in European blackjack, the hole card is not actually dealt until the players all play their hands).
The cards of the players are dealt either face up or face down, depending on local casino practice; face up is the most common.
At this point, if any player has a "natural" 21 (an Ace with any 10-count card), he is immediately paid 3:2 (most of the time: see Basic Strategy below) for his bet, unless the dealer also has a natural, which is a push.
If the dealer has a natural, all players without a natural lose immediately; they do not get a chance to further improve their hands.