Poker is a card game with many variants, but in all forms it involves betting between players to win the pot. The pot consists of all bets made during the current round. Each player must either call (match) or raise the bet. Players may also bluff, betting that they have a strong hand while hoping that opponents will fold.

The game is played using a standard deck of 52 cards. The aces are high, the kings, queens and jacks are low, and the other cards belong to four suits: spades, hearts, diamonds and clubs. Some variant games use more than one pack, or add extra cards called jokers.

After the flop, a fourth card opens on the table, known as the river. At this point, most of the players will know the strength of their hands. They can then decide to continue betting, call an opponent’s bet or fold their cards.

If no one calls, the player with the highest hand wins the pot. Players with ties split the pot. In some cases, the pot can be won by a “backdoor” flush, where an opponent with a pair of aces hits the turn and the river to make a straight.

Although the outcome of any individual hand in Poker is partly determined by chance, long-term expected value is based on decisions made by the players, which are influenced by probability, psychology and game theory. In addition, a good deal of skill is required to successfully bluff.