Official poker is a card game played by four or more players, with one or more cards dealt face up. The highest hand wins the pot. The game grew popular in the United States during the nineteenth century, and is today the most commonly played card game in the world. The game has several variants, some of which have become highly specialized and competitive.

A deck of standard 52-cards is used, and the rules for each poker variation usually specify which suits and rank the cards. The most common ranking of cards is ace, king, queen, and jack; there are four suits, spades, hearts, diamonds, and clubs. A few games allow the addition of wild cards, which can take on any suit and rank. Some poker games have a fixed limit, in which bets are determined by the number of cards that a player has.

During the 19th and early 20th centuries, a great deal of research was conducted into the history of card-games with the purpose of drawing up definitive sets of rules. This led to the publication of a book by R F Foster in 1904 called Practical Poker, summarizing the results of this research.

After the preflop betting round has ended, the dealer deals three cards face up on the table. These are known as the community flop cards. The remaining players may then decide whether to check, bet, raise, or fold. In some games, a player can request to see his opponent’s hand after it has been called. However, this privilege can be revoked by the player in question if it is abused.