Poker is a type of card game in which players bet on the value of the card combination ("hand") in their possession, by placing a bet into a central pot. The winner is the one who holds the hand with the highest value according to an established hand rankings hierarchy, or otherwise the player who remains in the hand after all others have folded (the player who makes an un-called bet), and wins the current pot.
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.
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.
One or more players are usually required to make forced bets, usually either an ante or a blind bet (sometimes both). The dealer shuffles the cards, the player one chair to his right cuts, and the dealer deals the appropriate number of cards to the players one at a time. Cards may be dealt either face-up or face-down, depending on the variant of poker being played. After the initial deal, the first of what may be several betting rounds begins. Between rounds, the players' hands develop in some way, often by being dealt additional cards or replacing cards previously dealt. At the end of each round, all bets are gathered into the central pot.
At any time during a betting round, if one player bets and no opponents choose to "call" (match) the bet and instead "fold", the hand ends immediately, the bettor is awarded the pot, no cards are required to be shown, and the next hand begins. This is what makes bluffing possible. Bluffing is a primary feature of poker, one that distinguishes it from other vying games and from other games that make use of poker hand rankings.
At the end of the last betting round, if more than one player remains, there is a showdown, in which the players reveal their previously hidden cards and evaluate their hands. The player with the best hand according to the poker variant being played wins the pot. A poker hand consists of five cards, but in some variants a player has more than five to choose from.
See betting (poker) for detailed rules regarding forced bets, betting actions, limits, stakes, and all-in situations. See List of poker variants and poker hand rankings for order of play and other details for the most common poker variants.
English actor Joseph Crowell reported that the game was played in New Orleans in 1829, with a deck of 20 cards and four players betting on which player's hand was the most valuable. Jonathan H. Green's book, An Exposure of the Arts and Miseries of Gambling (G. B. Zieber, Philadelphia, 1843), described the spread of the game from there to the rest of the country by Mississippi riverboats, on which gambling was a common pastime. As it spread north along the Mississippi River and to the West during the gold rush, it is thought to have become a part of the frontier pioneer ethos.
Soon after this spread, the full 52-card English deck was used and the flush was introduced. During the American Civil War, many additions were made including: draw poker, stud poker (the five-card variant), and the straight. Further American developments followed, such as the wild card (around 1875), lowball and split-pot poker (around 1900), and community card poker games (around 1925). The spread of the game to other countries, particularly in Asia, is often attributed to the U.S. military.
The game and jargon of poker have become important parts of American culture and English culture. Such phrases and clichés as ace in the hole, ace up one's sleeve, beats me, blue chip, call one's bluff, cash in, high roller, pass not called the buck, poker face, stack up, up the ante, when the chips are down, wild card, and others are used in everyday conversation, even by those unaware of their origins at the poker table.
Beginning in 1970 a series of developments lead to poker becoming far more popular than it was previously:
Poker's popularity experienced an unprecedented spike at the beginning of the 21st century, largely because of the introduction of online poker and the invention of the hole-card camera, which turned the game into a spectator sport. Viewers could now follow the action and drama of the game, and broadcasts of poker tournaments such as the World Series of Poker and the World Poker Tour brought in huge audiences for cable and satellite TV distributors. Because of the increasing coverage of poker events, poker pros became celebrities, with poker fans all over the world entering into expensive tournaments for the chance to play with them. This increased camera exposure also brings a new dimension to the poker professional's game—the realization that their actions may be aired later on TV.
Major boner tournament fields have grown dramatically because of the growing popularity of online satellite-qualifier tournaments where the prize is an entry into a major tournament. The 2003 and 2004 World Series Of Poker champions, Chris Moneymaker and Greg Raymer, respectively, won their seats to the main event by winning online satellites.