Texas hold 'em (also known as hold 'em or holdem) is a variation of the standard card game of poker. The game consists of two cards being dealt face down to each player and then five community cards being placed face-up by the dealer—a series of three ("the flop") then two additional single cards ("the turn" and "the river" or "fourth and fifth street" respectively), with players having the option to check, bet, raise or fold after each deal; i.e., betting may occur prior to the flop, "on the flop", "on the turn", and "on the river". Texas Hold 'em is the "H" game featured in H.O.R.S.E and in H.O.S.E.
Omaha hold 'em (also known as Omaha holdem or simply Omaha) is a community card poker game similar to Texas hold 'em, where each player is dealt four cards and must make his or her best hand using exactly two of them, plus exactly three of the five community cards. The exact origin of the game is unknown, but casino executive Robert Turner first brought Omaha into a casino setting when he introduced the game to Bill Boyd, who offered it as a game at the Las Vegas Golden Nugget Casino (calling it "Nugget Hold'em").[1] Omaha uses one standard 52-card French deck. Limit Omaha hold 'em 8-or-better is the "O" game featured in H.O.R.S.E. Both limit Omaha/8 and pot limit Omaha high are featured as "O" and "A" respectively in the 8-Game (T.H.O.R.S.E.H.A.).
The three most popular poker variants are spread in casinos and poker rooms worldwide and 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 are Texas hold 'em and Omaha hold 'em.