Poker is a card game of chance and skill that involves betting in rounds with one or more opponents. The game has many variants that differ in the number of cards dealt, whether they are face up or down, and the rules for determining a winning hand. Regardless of the specific rules, all poker games involve a minimum of one round of betting, during which each player has the option to call (match) a previous bet or fold and forfeit the amount bet so far.

Official poker games use standard 52-card packs, with some variants adding jokers or other special cards. A winning poker hand consists of five cards of rank (high, low, queen, jack, and 10), of a suit of spades, hearts, diamonds, or clubs. In addition to the cards, poker games also have betting limits, which control how much a player can raise on each round. These betting limits are usually no limit, pot limit, spread limit, or fixed limit.

Some poker games require a button, a token that is rotated among the players to indicate a nominal dealer. This is commonly used in casino poker rooms and some informal poker games to establish a player’s turn to act. Informally, this practice can prevent delays while players attempt to figure out change for a bet. However, casinos typically disapprove of the practice, as it can prevent a player from circumventing table limits by “ratholing” (taking away a portion of their stake for personal use) after winning a large pot and then buying back in with a smaller amount.