Poker is a card game in which players place an initial amount of money into the pot before being dealt cards. This amount is called the ante or blind, and it is required for all players to put up if they want to play. Players then bet in one round, with raising and re-raising allowed. The hand with the highest value wins the pot. Depending on the rules of the game, players may also be able to draw replacement cards for the ones in their hands after the first betting round.

While luck does play a role in the outcome of any given hand, poker is considered a game of skill as evidenced by the thousands of professional players who have generated positive long-term results. Furthermore, it is always regulated by set rules and customs, whether at a home game, in a casino cash game or at a World Series of Poker event. These rules generally prohibit string betting, betting out of turn and collusion, among others.

A successful book on poker must have a strong narrative and be well-written. This requires a deep understanding of the rules and strategy of the game, but it is especially important to be able to describe the action of a hand. This includes identifying which players are conservative and which are more aggressive, and which players are showing tells, unconscious habits that reveal information about their hands. These can be as simple as a change in posture, facial expression or gesture.