Blackjack is a variation of the French game vingt-et-un, or 21. Like the British variant, pontoon, the aim is to beat the banker to a maximum score of 21. The old British card-shedding game of blackjack is no relation.
Early American casinos offered a bonus if a player was dealt a black jack and the ace of spades, hence the name. Nowadays, with the bonus withdrawn, “blackjack” still refers to a hand with any ten or face card plus any ace.
On a wide table, the banker deals two cards face up to each player. The banker’s first card is dealt face up, and the second is dealt face down. The players can request a “hit” – in which case they will receive another card – they can “stand” and keep just the cards they have, or they can “double down” – double the bet, take a single card, and stay with that. It is also possible to “split” – run two hands off the first deal if both cards are equal – for instance, two kings, or two 9s. A player may take more cards, trying to not “bust” by exceeding a total of 21, in which case they forfeit their bets. When all players are done, the banker’s hand is played out; in most instances, the banker must have a minimum of 17 to stay. The bank never doubles but can bust, pays out on better hands, returns bets on the same score, and collects on lower scores.
Blackjack is normally played with multiple packs of cards dealt from “shoes”, with used cards discarded, which encourages players to count remaining cards to improve their chances of winning. Blackjack offers players one of the lowest “house edges” of any casino game.