Texas Hold 'em

A dealer "button" is used in Hold'em to indicate the position of the player who would be dealing the cards if the players were actually dealing the cards themselves. The player holding the button acts last and thus has a positional advantage that remains throughout the hand. After each hand, the button is moved one position clockwise, so that all players in the game have, after a full round, had exactly the same number of opportunities to hold positional advantage.

The two players on the button's immediate left must post "blind" bets. Typically, the player in the very first position posts a blind bet one-half the size (called the "small blind") of the player in the second position and the second player posts a bet (called the "big blind").
All participants are now dealt two cards face down. A round of betting takes place during this point, which is called "before the flop" or "pre-flop."
In the pre-flop betting round, the player in third position has only three choices. Because a blind wager has already been made, the player can do any of the following:

Fold. If the third player folds, he is out of the hand permanently, and cannot participate again until the next deal of the cards
Call, by matching the size of the big blind; or
Raise. How much the player can raise depends on whether the game is limit, pot-limit, or no-limit.

The action continues in clockwise fashion around the table, with each player in turn having the option to call, raise or fold. If the third or another player has raised, the player who acts after the raiser must now decide whether he wishes to call $20, or raise to $30.

With the pre-flop betting complete, the dealer now deals out three cards face-up. These are "community" cards that belong to everyone, and these three cards are called "the flop." A second round of betting follows.

In the second betting round, the player closest to the left of the button, who is still in the hand, acts first. Unlike the first betting round, though, where the options were "call, raise or fold," now the options are:

Check, which means to decline to wager now but to retain the option to call or raise bets made by other players; or
Bet.

It is possible, and indeed happens reasonably often, that all players still in the hand will check, meaning that there is no betting action on the flop. But if someone bets, the players must decide whether they are going to call or raise, and the same limit on the number of raises in a round applies.

After the third round betting concludes, the dealer reveals a fourth community card, called "the Turn" or "Fourth Street." In limit poker, the size of the betting amount now doubles, for example, up to $20 (which is why this game is called a "10-20" game). The greater bet size aside, the process of betting and checking is identical to that on the flop.

After this third round of betting concludes, the dealer reveals the fifth and final community card, called "the River," or "Fifth Street." Betting is identical to the pattern used on the third (Turn) round.

At the end of this fourth round of betting, any players still remaining in the hand turn their cards over. (If at any point during the hand, one player makes a bet that all others decline to call, the hand is over immediately, and the player who made the final wager takes the pot without the need to show his cards.)

The player who can assemble the best five-card hand, out of the seven possible (the two in their hands and the five in the middle) wins the pot. The players can thus use two, one, or none of their "private" first two cards. Although it is unusual to use none of one's private cards, it is possible, if the five cards on the board form a strong hand such as a straight, flush, or full house.

Omaha

Omaha is a form of Hold 'Em but it has a few differences still. Players are dealt four cards face down before the flop but only two of these cards must be used combined with three cards from the board to form a best five-card poker hand.

Omaha uses a dealer button and blinds as in Texas Hold 'Em but it's a nine-card poker game. Action starts with the first player to the left of the blinds beginning the betting. Players may bet, check, raise, or fold in turn.

Community cards are then dealt face up the same as in Texas Hold 'Em with betting after each round.

After the final betting round, the players remaining in the hand will then show all their cards. The best poker hand wins and is awarded the pot.

Seven Card Stud

Each player gets two cards face down and one card face up, in Seven-Card Stud. The player with the low card opens the betting. All players in turn must call, raise, or fold. Then the player who has the best hand opens the betting on all the following rounds.

Each player is then dealt 3 cards face up. Players may bet after each card appears.
The last dealt card is face down with the final betting round following.

Those players why haven't folded will then show their hands and the winning poker hand will be awarded the pot. The tied hands will split the pot.