Poker is a card game in which players place bets (or ‘chips’) and aim to make the best five-card hand. There are many different forms of the game, but most have some common features. Each player starts with two cards and has ‘chips’ to bet with; he must place these in the pot before a 5th card is dealt (known as the ‘river’). The winner of each deal wins the ‘pot’, which includes all the bets made up to that point.

During the betting intervals, it is possible for a player to raise his stake by matching or raising that of the last active player, in order to stay in the pot. This is known as calling. If a player cannot meet this requirement, he must fold; otherwise he can continue to raise until he can.

In addition to raising, it is often important to bluff at the right time. For example, a player with a low pocket pair on the flop may try to get other players to commit more money to the pot by checking, hoping that they will assume that he has a high-ranking hand.

Some players use the game to practice their psychological skills, such as examining their opponents’ reactions and reading their body language. Others play poker as a form of entertainment or social interaction. There are also debates about whether poker creates or exacerbates negative qualities such as aggression, narcissism, and insecurity, or if it provides an acceptable outlet for these traits.