Poker is a card game for two to 14 players with a variety of betting rounds and possible outcomes. A hand consists of five cards, and winning the pot is determined by a combination of the best poker hands according to the specific game rules. The highest ranking poker hand is a royal flush, which comprises the 10, jack, queen, king and ace of one suit (clubs, diamonds, hearts or spades). In some poker games the joker—here called a bug—also counts as an ace but only in a straight or certain other poker hands.

While any particular poker hand largely involves chance, a great deal of the long-run expectation at the very top levels of the game is derived from action chosen on the basis of probability, psychology and poker theory. A poker player must understand how their opponents think and act during a hand, including reading tells (e.g. how they move their chips around the table).

The turn to deal and bet is passed in rotation from one player to the next. A player may cut the pack before dealing if they wish to do so. If the player who cuts is the dealer, he must offer the shuffled pack to his opponent to his left for a cut on each deal. If that player declines to cut, any other player may do so. There are many different variations of poker, but the majority of them use the same basic set of rules.