Poker is a card game in which players place a bet, then reveal their cards and compete for the pot. Each player has the choice to call, raise or fold, based on their best estimate of the probability of winning the hand. Although much of a game of poker is chance, skillful players maximize their long-run expectations through decisions made on the basis of probability, psychology and game theory.

Each game is played with a standard 52-card pack, although some games use more than one pack or add a few jokers as wild cards. Cards are ranked in order from high to low: ace, king (K), queen (Q), jack (J), 10, nine, eight, seven, six, five, four and three. Most poker games allow two to seven players.

When betting begins, each player must ante a specified amount (typically a dime or less). Then each player is dealt five cards face down. When betting is completed, the highest hand wins the pot. Players may discard their cards and draw new ones, or they can choose to remain in the hand by calling a bet (called opening).