Although Texas Holdem has become very popular lately, it has been around for a while. It was introduced into Las Vegas in the 60s at Golden Nugget and has become what it is today from there. The Holdem main event is also held in Las Vegas.
Blinds - First off the player must put in their blinds. The player to left of the dealer puts in the "small blind", the player to the left of them places the "big blind", which is twice the value of the small blind. Then each player is dealt two cards. The rest of the players get to look at their cards before they place their blinds. They players are also allowed to raise the blinds as high as they like depending on whether the game is no limit or not. When all the other players have entered their blinds the small blind player then has to top up the amount to continue, and the big blind player has the right to "push", i.e. raise the blinds. This is the first round of betting.
The Flop - Next a dead card is dealt, this will not be seen by any of the players at all, and then three more cards will be dealt face up. These three cards are referred to as the flop. At this stage each player now has 5 cards they can use to make a hand, three on the flop and two in their hand. Another betting round will start from the small blind player.
The Turn - once the second betting round is finished another card is turned dead, and another card is turned up. This stage of the game is known as the Turn. Again another betting round will occur, starting from the small blind.
The River - another dead card is played, and then another card turned over, this is the last card know as the River. This leaves 5 cards on the table and 2 cards in the players hand. From here the players can work out what hand they have by creating the best 5 cards from the 7 available to them.
No Limit - some games require a limit which means you can only raise as much as the big blind, others have no limit.
Tournaments - tournaments are common with Texas Holdem, where everyone buys in for an agreed upon amount and try to last in the tournament for as long as they can. The higher up they rank, the more they win in prize money.
Omaha is a deviation to the original Texas Holdem. The difference is that each player is dealt 4 cards instead of 2. However, the player can, and must, only use 2 of their cards. Even if they have been dealt four aces, they can only use two of them. This also means that they must use only 3 cards that are on the table, and no more.