Poker is a card game in which players place bets and try to win the pot by having the highest-ranking hand at the end. Although countless variations of poker exist, most are played with five cards and involve betting. Players can also bluff by betting that they have the best hand, which causes other players to either call (match) the bet or fold.

The rules of poker vary slightly from one variation to the next, but there are some fundamental aspects common to most: Players must ante before they can get dealt cards. Then, they must place bets into the central pot during each round of betting. The player with the highest hand at the end of the round wins the pot.

A player may say “call” to match the last person’s bet, or “raise” to add more money to the pot. If a player wants to fold, they can simply turn their cards into the dealer.

The value of a poker hand is determined in inverse proportion to its mathematical frequency: the more unusual the combination of cards, the higher the rank of the poker hand. The highest poker hand is a royal flush, consisting of an ace, king, queen, jack and ten of the same suit.

While von Neumann’s proof of the “Theory of Games” led to advances in the mathematics of auctions, submarine warfare and even the way species compete to pass on their genes, it took many more years for researchers at the University of Alberta to solve the problem of a simple game like checkers. This led to the development of computer programs that have surpassed human ability to beat checkers, a breakthrough that enabled researchers to apply the lessons of the theory to games like poker and Go.