How to Play Poker Like a Superhuman

Poker is a card game in which players place bets (representing money) into a pot based on the strength of their hands. It is played in casinos, private homes, and on the Internet, and has been described as the national card game of the United States. Its play and jargon have permeated American culture.

The game consists of betting rounds and a showdown, in which all active players reveal their cards. The highest ranked hand wins the pot. Other hands may tie, in which case the winners share the prize. Ties are broken by the rank of unmatched cards (in a flush) or by secondary pairs (in a full house).

A pair is two matching cards of the same rank, three of a kind is three cards of the same rank and two unmatched cards, and a straight is five consecutive ranks in one suit. A royal flush is four of a kind and an ace.

Professional poker players are experts at extracting signal from noise and at integrating information about their opponents both to exploit them and to protect themselves. They use a variety of tools, including software and other resources, to create behavioral dossiers on their opponents and even to collect or buy records of other players’ hands.

Because poker involves imperfect information—players know their own cards but not those of their opponents—it is more difficult to model than chess, and it took longer to develop the first superhuman AI for it. Nevertheless, in 2015 computer scientists announced that an algorithm had demonstrated essentially perfect play for a limited version of the game with only two players and constrained bet sizes.