Poker is a card game in which players place bets based on probability, psychology and game theory. The objective is to win the pot, which is the sum of all bets placed during a deal. Players can win this money by having a high ranking poker hand or by betting aggressively in order to make others fold their hands. Usually there are rules agreed before the game begins on how this money will be shared between the winning player and the other players who did not have a good hand.

When the game is in progress, each player is dealt cards one at a time by the dealer. The card is face down and the player may choose to show their cards or not. Then a series of betting intervals occurs. Each betting interval starts with the player to the left of the dealer making a bet. Other players may call this bet or raise it. A player may also drop their hand, meaning they will not put any chips into the pot until the next betting round.

Some of the early rules in poker are debated, such as its origins and whether it came from the 17th century Persian game As-Nas or from a European game like French Tarot. The game was further developed and spread around the world by American soldiers after the Civil War. In this period, the full 52-card English deck was introduced and a variation – Stud Poker – appeared.