Poker is a card game for two or more players with a goal of winning a pot (the sum of all bets) by having the highest-ranking hand at “showdown.” In the most common form, each player buys in for the amount of chips he wishes to risk.

The rules of the game differ, but the basic strategy is based on minimising losses by calling bets with weak hands and raising bets with strong ones. Players can also bluff, but the more information they have about their opponents’ actions, the more likely they are to make the right decisions.

A number of early vying games may have contributed to the development of Poker, but articles focusing on poker suggest that it first became popular in the mid-19th century after it had spread northward along the Mississippi River and westwards with the frontier, and that its expansion coincided with the introduction of 52-card packs. It is also suggested that the game benefited from its adoption by Brag, which introduced the draw as an additional way to improve a promising hand.

As the game became increasingly popular, a flurry of research into its history and strategy developed. For example, in 1944 the mathematician John von Neumann and the economist Oskar Morgenstern published a foundational book that analysed a simplified variant of the game. Their work demonstrated that the game can be reduced to a finite number of moves, and that an optimal strategy exists.