Poker

Poker is any of a number of card games in which players wager over which hand is best according to that specific game's rules in ways similar to these rankings. Often using a standard deck, poker games vary in deck configuration, the number of cards in play, the number dealt face up or face down, and the number shared by all players, but all have rules that involve one or more rounds of betting.

In most modern poker games, the first round of betting begins with one or more of the players making some form of a forced bet (the blind or ante). In standard poker, each player bets according to the rank they believe their hand is worth as compared to the other players. The action then proceeds clockwise as each player in turn must either match (or “call”) the maximum previous bet, or fold, losing the amount bet so far and all further involvement in the hand. A player who matches a bet may also “raise” (increase) the bet. The betting round ends when all players have either called the last bet or folded. If all but one player folds on any round, the remaining player collects the pot without being required to reveal their hand. If more than one player remains in contention after the final betting round, a showdown takes place where the hands are revealed, and the player with the winning hand takes the pot.

With the exception of initial forced bets, money is only placed into the pot voluntarily by a player who either believes the bet has positive expected value or who is trying to bluff other players for various strategic reasons. Thus, while the outcome of any particular hand significantly involves chance, the long-run expectations of the players are determined by their actions chosen on the basis of probability, psychology, and game theory.

Poker has increased in popularity since the beginning of the 20th century and has gone from being primarily a recreational activity confined to small groups of enthusiasts to a widely popular activity, both for participants and spectators, including online, with many professional players and multimillion-dollar tournament prizes. 

Poker was developed sometime during the early 19th century in the United States. Since those early beginnings, the game has grown to become an extremely popular pastime worldwide.

In the 1937 edition of Foster's Complete Hoyle, R. F. Foster wrote: “the game of poker, as first played in the United States, five cards to each player from a twenty-card pack, is undoubtedly the Persian game of As-Nas.” By the 1990s some gaming historians including David Parlett started to challenge the notion that poker is a direct derivative of As-Nas. Developments in the 1970s led to poker becoming far more popular than it was before. Modern tournament play became popular in American casinos after the World Series of Poker began, in 1970. Poker on television increased the popularity of the game during the turn of the millennium. This resulted in the poker boom a few years later between 2003–2006.

In casual play, the right to deal a hand typically rotates among the players and is marked by a token called a dealer button (or buck). In a casino, a house dealer handles the cards for each hand, but the button (typically a white plastic disk) is rotated clockwise among the players to indicate a nominal dealer to determine the order of betting. The cards are dealt clockwise around the poker table, one at a time.

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 on the chair to his or her right cuts, and the dealer deals the appropriate number of cards to the players one at a time, beginning with the player to his or her left. 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, no opponents choose to call (match) the bet, and all opponents 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 comprises five cards; in variants where a player has more than five cards available to them, only the best five-card combination counts. There are 10 different kinds of poker hands, such as straight flush and four of a kind.