Poker is a card game in which players place bets by raising or folding their cards. The object is to win the pot, which is the sum of all bets made during a hand. Players may also bluff, betting that they have the best hand when in fact they do not. The game can be played by two to fourteen people, with the ideal number being six or seven.
There are many variants of poker, but most share certain essential features. For example, a hand must consist of five cards; the rank of each card is determined by its mathematical frequency; the suits have no value; and ties are broken using the rules of High Card.
The right to deal and bet passes clockwise from player to player. The last player to deal a hand is the button (or buck). This position may be assigned a different person each round in casual play, or the same person every time in a casino. A shuffle is mandatory before each hand, and the deck may be cut by any player.
Observing other players for tells can be helpful in reading the game. Shallow breathing, sighing, flaring nostrils, an increasing pulse seen in the neck or temple, blinking excessively, and shaking hands can reveal nervousness or a weak hand. A player who holds a hand over his mouth or chews gum may be trying to conceal a smile. A player who raises bets early in a hand is called an aggressive player; these players can be more easily bluffed into folding their cards by other players with superior hands.