Blackjack (also known as Twenty-one, Vingt-et-un (French for Twenty-one), or Pontoon is the most widely played casino banking game in the world. Much of blackjack’s popularity is due to the mix of chance with elements of skill, and the publicity that surrounds card counting (calculating the probability of advantages based on the ratio of high cards to low cards). The casino version of the game should not be confused with the British card game Black Jack (a variant of Crazy Eights).
Blackjack’s precursor was “twenty-one,” a game of unknown origin. The first written reference is to be found in a book of Miguel de Cervantes, the author of Don Quixote, and a gambler himself. The main characters of his tale “Rinconete y Cortadillo”, from “Novelas Ejemplares”, are a couple of cheaters working in Seville. They are proficient at cheating at “veintiuna” (Spanish for twenty-one), and stated that the object of the game is to reach 21 points without busting, and that the Ace values 1 or 11. The game is played with the Spanish deck, that is without tens, which makes the game similar to the current Spanish 21. This short story was written between 1601 and 1602, so the game was played in Castilia since the beginning of the 17th Century or even earlier. Later references of this game are to be found in France and Spain.

When 21 was first introduced in the United States it was not very popular, so gambling houses tried offering various bonus payouts to get the players to the tables. One such bonus was a 10-to-1 payout if the player’s hand consisted of the ace of spades and a black Jack (either the Jack of clubs or the Jack of spades). This hand was called a “blackjack” and the name stuck to the game even though the bonus payout was soon abolished. As the game is currently played, a “blackjack” may not necessarily contain a jack or any black cards at all.

In casino blackjack, the dealer faces one to seven players from behind a kidney-shaped table. Each player plays his hand independently against the dealer. At the beginning of each round, the player places a bet in the “betting box” and receives an initial hand of two cards. The object of the game is to get a higher card total than the dealer, but without going over 21 which is called “busting” or “too many.” (The spot cards count 2 to 9; the 10, jack, queen, and king count as ten; an ace can be either 1 or 11 at the player’s choice). The player goes first and plays his hand by taking additional cards if he desires. If he busts, he loses. Then the dealer plays his/her hand. If the dealer busts, he/she loses to all remaining players. If neither busts, the higher hand total wins. In case of a tie, no one wins – the hand is a “push” and all bets are returned. It is possible for the dealer to lose to some players but still beat other players in the same round.
Example of a Blackjack game. The top half of the picture shows the beginning of the round, with bets placed and an initial two cards for each player. The bottom half shows the end of the round, with the associated losses or payoffs.

Cards are dealt in three ways, either from one or two hand-held decks, from a box containing four to eight decks called a “shoe,” or from a shuffling machine. When dealt by hand, the player’s two initial cards are face-down, while the dealer has one face-up card called the “upcard” and one face-down card called the “hole card.” (In European blackjack, the hole card is not actually dealt until the players all play their hands.) When dealt from a shoe, all player cards are normally dealt face-up, with minor exceptions. It shouldn’t matter to the player whether his cards are dealt face-down or face-up since the dealer must play according to predetermined rules. If the dealer has less than 17, she must hit. If the dealer has 17 or more, she must stand (take no more cards), unless it is a “soft 17″ (a hand that includes an ace valued as “11,” for example a hand consisting of Ace+6, or Ace+2+4). With a soft 17, the dealer follows the casino rules printed on the blackjack table, either to “hit soft 17″ or to “stand on all 17’s.”

The highest possible hand is a “blackjack” or “natural,” meaning an initial two-card total of 21 (an ace and a ten-value card). A player blackjack is an automatic winner unless the dealer also has blackjack, in which case the hand is a “push” (a tie). When the dealer upcard is an ace, the player is allowed to make a side bet called “insurance,” supposedly to guard against the risk that the dealer has a blackjack (i.e., a ten-value card as her hole card). The insurance bet pays 2-to-1 if the dealer has a blackjack. Whenever the dealer has a blackjack, she wins against all player hands except those that also have a blackjack (which are a “push”).

The minimum and maximum bets are posted on the table. The payoff on most bets is 1:1, meaning that the player wins the same amount as he bets. The payoff for a player blackjack is 3:2, meaning that the casino pays $3 for each $2 originally bet. (There are many single-deck games which pay only 6:5 for a blackjack.)

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Poker is a family of card games that share betting rules and usually (but not always) hand rankings. Poker games differ in how the cards are dealt, how hands may be formed, whether the high or low hand wins the pot in a showdown (in some games, the pot is split between the high and low hands), limits on bets and how many rounds of betting are allowed. In most modern poker games, the first round of betting begins with some form of forced bet. The action then proceeds to the left. Each player in turn must either match the maximum previous bet or fold, losing all further interest in the hand. A player who matches a bet may also raise, increasing the bet. The betting round ends when all players have either matched the last bet or folded. If all but one player fold on any round, the remaining player collects the pot without showing his hand. If more than one player remains in contention after the final betting round, the hands are shown and the winning hand takes the pot.

Players feel that this betting system distinguishes poker from gambling games. With the minor exception of initial forced bets, money is only placed into the pot voluntarily by a player who, at least in theory, rationally believes the bet has positive expected value. Thus while the outcome of any particular hand is determined mostly by chance, the long-run expectations of the players are determined mostly by their actions chosen based on probability and psychology.

Poker has many variations, all following a similar pattern of play and generally using the same hand ranking hierarchy. There are three main families of variants, largely grouped by the protocol of card-dealing and betting:

Straight: A complete hand is dealt to each player, and players bet in one round, with raising and re-raising allowed. This is the oldest poker family; the root of the game as currently played was a game known as Primero, which evolved into the game Three-card brag, a very popular gentleman’s game around the time of the American Revolutionary War and still enjoyed in the U.K. today. “Straight” hands of five cards are sometimes used as a final showdown, but poker is currently virtually always played in a more complex form to allow for additional strategy.

Stud: Cards are dealt in a prearranged combination of face-down and face-up rounds or “streets”, with a round of betting following each. This is the next-oldest family; as poker progressed from three to five-card hands, they were often dealt one card at a time, either face-down or face-up, with a betting round between each. The most popular stud variant today, Seven-card stud, deals two extra cards to each player (three facedown, four faceup) from which they must make the best possible 5-card hand.

Draw: A complete hand is dealt to each player, face-down, and after betting, players are allowed to attempt to change their hand (with the object of improving it) by discarding unwanted cards and being dealt new ones. Five-card draw is the most famous variation in this family.

Community: A variation of Stud, players are dealt an incomplete hand of face-down cards, and then a number of face-up “community” cards are dealt to the center of the table, each of which can be used by one or more of the players to make a 5-card hand. Texas hold-em and Omaha are two well-known variants of the Community family.

Other games that use poker hand rankings may likewise be referred to as “poker”. Video poker is a single-player computer game that functions much like a slot machine; most video poker machines play draw poker, where the player bets, a hand is dealt, and the player can discard and replace cards. Payout is dependent on the hand resulting after the draw and the player’s initial bet.

Strip poker is a traditional poker variation where players remove clothing when they lose bets. Since it depends only on the basic mechanic of betting in rounds, strip poker can be played with any form of poker; however, it is usually based on simple variants with few betting rounds, like five card draw.

Another game with the “Poker” name, but with a vastly different mode of play, is called “Acey-Deucey” or “Red Dog” Poker. This game is more similar to Blackjack in its layout and betting; each player bets against the house, and then is dealt two cards. For the player to win, the third card dealt (after an opportunity to raise the bet) must have a value in between the first two. Payout is based on the odds that this is possible, based on the difference in values of the first two cards.