Poker is a card game in which players bet against each other based on the strength of their hands. The game is played in several betting intervals, and each player must place a number of chips into the pot, or bet, to have the opportunity to make a hand. The best hand wins the pot.

The rules of poker vary depending on the game variant being played, but there are certain fundamental principles that apply to all games. Generally, a player must act in a way that maximises his expected winnings and minimises his losses – this is called MinMax. This involves a combination of probability, psychology and game theory.

Most forms of poker are played with a fixed number of cards and a fixed amount of money, which is collectively known as the pot. In most cases the pot is won by a player who has the highest-ranking poker hand at showdown. However, it is also possible for a player to win the pot by making a bet that no other player calls.

Despite many erroneous claims to the contrary, Poker cannot be said to be older than playing-cards themselves, which were first positively attested in 13th century China (though evidence for their origin dates back a few centuries earlier). By the 1830s, it had spread northwards along the Mississippi and westwards into the American frontier, adopting its anglicized name from Brag, and becoming increasingly popular in riverboats and game parlors.