Poker is a card game in which players wager money on a hand of five cards. Bets may be made in one round with raising and re-raising permitted. The highest hand wins the pot. Poker has numerous variants, but the basic game consists of an ante and several rounds of betting. The game has become popular worldwide and is considered a card game of skill. Professional poker players are able to gain an advantage over their opponents through the use of bluffing and information about their opponent’s tendencies.

A standard pack of 52 cards is used in most games, with some adding jokers. The cards are ranked (from high to low) as follows: Ace, King, Queen, Jack, 10, 9, 7, 6, 5, 4, 3, 2. The highest hand is a royal flush of matching suits; this is sometimes called an A-K-Q-J-T-A. Other high hands include a straight of five consecutive cards, and a three of a kind, also known as a full house.

Although the outcome of any given hand largely depends on chance, the game is based on the principle that a player’s long-run expected value from a bet is determined by actions chosen on the basis of probability, psychology and game theory. Unlike other casino games, in which bets are forced, the amount of money placed into the pot is entirely voluntary. Players may choose to call a bet only when they believe that they have a superior hand or to bluff in the hope that other players will fold before the showdown.