Poker is a card game in which players place bets against one another. The goal is to win a pot, or the sum of all bets placed during a hand, by having a winning combination of cards. Unlike other games of chance, poker allows for strategic play based on probability and psychology. In addition, it is a game of incomplete information; players must commit resources before all facts are known, and there are often hidden factors that influence other players.

A player must place an initial forced bet (the ante or blind bet) to participate in a hand. Each player then receives two personal cards and the community cards on the table. This is known as a “showdown” hand. The cards are revealed on the flop, turn, and river. The best five-card hand wins the pot. The cards must be of the same suit to form a straight or flush.

After the first betting round, a player may draw additional cards from the deck to improve his or her hand. Depending on the rules of the game, replacement cards are also dealt to the table. Whether or not the dealer deals replacement cards is usually determined by the button, which is the position of the player to the left of the player who shuffles and deals the cards.

The game originated from an earlier vying game called Poque and was later spread by French culture to America, where it was adapted to various forms. It is notable for being an important early example of a game that could be mathematically analyzed and optimized. The 1944 book Theory of Games and Economic Behavior by mathematician John von Neumann and economist Oskar Morgenstern used the game of poker as a key example in their analysis of game theory.