Poker is a card game where players wager money (or chips) against each other. The goal is to win the pot, which is the total of all bets placed in a single deal. This is accomplished by having a higher-ranking hand than your opponents.

A high-ranking hand consists of two or more cards that are the same, and at least one card must be an ace. This includes straights, flushes, and three-of-a-kind. A pair of matching cards is also considered a strong hand, while a full house consists of three matching cards in one rank and two matching cards in another. The highest possible hand is the royal flush, which consists of an ace, king, queen, jack, and 10 of the same suit.

Before a poker hand is dealt, each player must place an initial contribution into the pot. This is called putting in the ante. The amount of the ante varies by poker variant, but is usually somewhere in the range of one to five chips. Once all players have contributed, the cards are dealt. Each player has the option to raise or fold after placing their bet.

In most forms of poker, the player to the immediate left of the button begins the betting. The button passes clockwise after each hand. The person to the left of the button can call the bet or raise it, but if they do not, their turn passes to the next player.

Once the bets are placed, the highest-ranking hand wins the pot. In some cases, however, multiple hands may tie for the same prize. In these cases, the winner is determined by looking at the cards in each hand. If the hands contain identical pairs, the ranking of the fifth card determines the winner.

The rules of poker are very simple, but mastery requires skill and a deep understanding of the psychology of the game. A good poker player must know when to bluff, when to make calls, and how much to risk on each hand. A good player can also recognize his or her opponents’ betting patterns and tells, and exploit these weaknesses.

The mathematical foundations of poker were laid by John von Neumann’s “Theory of Games,” which predicted that many of the complex interactions between competitive agents could be modeled using a combination of probability and game theory. The field of game theory has since developed to include not only poker, but chess, go, StarCraft, and even the way species compete to pass their genes on to future generations.