Poker is a card game that involves betting between several players. It is a family of card games whose rules vary according to the particular variation being played. Poker is very popular in the United States, where it has become a national pastime and has influenced many other card games, sports, and cultural activities.

In a standard game of poker, the cards are dealt clockwise around the table and each player places an initial contribution to the pot, known as the blind or ante. Then, in one round of betting, each player must either call (match) the highest previous bet or raise it. A player who calls a bet may also choose to check, in which case he or she forfeits the amount already contributed to the pot and all further involvement in the hand.

The winner of the pot is awarded to the player with the best poker hand. The best hands are usually high-ranked pairs, three of a kind, or four of a kind. If the hands are identical, then the higher ranking card breaks the tie. The lowest ranked cards are used to break ties in some poker variations, such as the bug, which uses a 53-card pack with the joker counting only as a wild card for a straight, a flush, or certain special hands. In some variants, the highest and lowest hands split the pot; this is called a high-low split. In most poker variants, the hand rankings are established by rule.