Poker is a card game in which players bet that their cards are better than those of their opponents. The value of a hand is in inverse proportion to its mathematical frequency; thus, very rare combinations of cards are rated highly. Players may also win by bluffing, betting that they have a superior hand when in fact they do not, hoping that opponents will call their bets.

Depending on the rules of the game, players must place an initial amount of money into the pot before the cards are dealt. These bets are called antes, blinds or bring-ins. Some games also allow players to exchange some or all of their cards during the “flop” and “river” stages of play, but this is not common in professional poker games.

Expert poker players have quick instincts and use their experience to predict how other players will react to various situations. They are adept at extracting signal from noise across many channels, including visual cues such as body language and eye contact. They also build behavioral dossiers on other players and, in some cases, purchase records of previous hands to improve their own strategy. In addition, they keep track of the rake taken by the gaming room or site (a percentage of every pot) to determine how much they should be betting. They also keep meticulous records of their winnings and losses, as well as any taxes they must pay on their gambling income.