"Holdem" is a family of poker games (Texas Hold'em, Omaha) with common structure and betting characteristics.
Each player is dealt some number (depending on kind of a game; for example, in Texas Hold'em - two, in Omaha - four) of cards ("hole cards") which belong only to that player. Five community cards are dealt face-up on the "board". All players may use these cards in conjunction with their own hole cards to make the best five-card poker hand possible.
In "Hold'em", a disc also known as "the button", serves to indicate which player is the nominal dealer for the current game. Before the game begins, the player immediately clockwise from the button posts the "small blind", typically half a small bet (for example, $1 in a $2/$4 game). The player immediately clockwise to the small blind posts the "big blind", which is always a full small bet (for example, $2 in a $2/$4 game). Now, each player receives his or her hole cards. Betting action proceeds around the table, starting with the player immediately clockwise to the big blind.
Players may now fold, check, call the big blind, or raise. In Limit games, the raise is limited to one small bet. In Pot Limit the maximum raise is the pot (the amount currently in the pot, plus his call), whereas in No Limit the maximum raise can be any amount of chips.
Now, the "flop" is dealt face-up on the board. The flop is the first three community cards available to all active players. Betting begins with the active player immediately clockwise the button. Again, in Limit games, all bets and raises at this point occur in small bets (increments of $2 in a $2/$4 game).
When betting action is completed for the flop round, the "turn" is dealt face-up on the board. The turn is the fourth community card in a "Hold'em" game. Betting begins with the active player immediately clockwise the button. On this round in Limit games, betting doubles from the small bet to the big bet. In a $2/$4 game, betting on the turn is done in $4 increments.
When betting action is completed for the turn round, the "river" is dealt face-up on the board. The river is the fifth and final community card in a "Hold'em" game. Betting begins with the active player immediately clockwise from the button.
If there is more than one remaining player when the final betting round is complete, the last bettor or raiser shows his or her cards. If there was no bet on the final round, the player immediately clockwise the button shows his or her cards first. The player with the best five-card hand wins the pot. In the event of identical hands, the pot will be equally divided between the players with the best hands.
After the pot is awarded, a new game of "Hold'em" is ready to begin. The button now moves clockwise to the next player.