The game of poker has many variations, most of them created in the United States in the mid-1900s. The standard order of play applies to most of these games, but to fully specify a poker game requires details about which hand values are used, the number of betting rounds, and exactly what cards are dealt and what other actions are taken between rounds. Any game may also use any betting structure.

They can be divided into the following groups:

• Draw poker: Games in which players are dealt a complete hand, hidden, and then improve it by replacing cards. The most common of these is Five-card draw.
• Stud poker: Games in which each player receives a combination of face-up cards and face-down cards in multiple betting rounds. The most common of these are Seven-card stud and Five-card stud.
• Community card poker: Games in which each player's incomplete hidden hand is combined with shared face-up cards. The most common of these is Texas hold 'em. See also: Omaha hold'em.
• Miscellaneous poker: Other games, or hybrids of the foregoing games.

It is not uncommon for players in home games to invent ad-hoc variants during a playing session. Such games rarely achieve the popularity of the well-known variants, for the good reason that the well-known variants have have been selected for playability over many years. "Playability" varies with the players, though, so it is quite common for a single group of players with shared tastes to become accustomed to one of these variants. When joining an established group as a new player, it is important to fully understand the rules of any such game that they commonly play.

see also: Non-standard poker hands