Poker is the card game in which players wager against each other by putting chips (representing money) into a common pot. The game can be played socially for pennies or matchsticks, or professionally for thousands of dollars. The outcome of any particular hand depends to a large degree on luck, but the long-run expectations of players are determined by their actions chosen on the basis of probability, psychology and game theory.

After each player receives two hole cards, there is a round of betting. The first bet, which is mandatory for all players, is placed into the pot by the player to the left of the dealer. The rest of the players may either call the bet, raise it or fold. Players can also choose to “bluff” – pretend that they have a stronger than average hand, and win by forcing opponents to fold.

Before a new hand is dealt, the players usually establish a fund, called a kitty, to pay for replacement decks of cards and refreshments. During the course of a hand, the kitty is built up by “cutting,” which involves taking one low-denomination chip from each pot in which there is more than one raise. When the hand ends, any chips left in the kitty are divided equally among the players still in the game.

Professional players use a combination of techniques to extract signal from noise, including their own body language, to understand the tells of their opponents. They can then use this information to exploit and defend against them.