Omaha is one of the most popular types of poker.
There are several rounds to the game, and the player who produces the strongest 5-card hand (or the one to make all the other opponents fold) ends up the winner. This player bags all the bets put forward by all other participating players, i.e. wins the pot.
 
Omaha is pretty similar to Texas Hold 'Em, but there are 2 key differences:
1. Each player is dealt 4 hole cards, not 2.
2. Each player is to produce a hand using strictly 2 of their hole cards and 3 community cards from the table.
 

General Info

A standard 52-card pack is used for the game, with ranks ascending from a Two to an Ace. The Ace is somewhat peculiar in a sense that it can act both as the highest or the lowest card of the sequence (see Straight and Straight Flush hands for more on that).
Card suits play no role in determining the rank of a hand.
 

Hands

It is essential to memorize the ranks of card hands to make it in the game of poker. In Omaha, the hands are identical to Texas Hold 'Em.
You should also remember that while a hand is always a combination of 5 cards exactly, as is in Texas Hold 'Em, it must put together by using strictly 3 community cards and 2 hold cards when you're playing Omaha. 
 
Here are the hands ranked in descending order, from highest to lowest:
  • Royal Flush: 5 highest cards of the same suit (Ace, King, Queen, Jack, Ten);
  • Straight Flush: 5 cards of the same suit in a row other than the 5 highest that make up a Royal Flush (remember?);
  • Four of a Kind: 4 cards of the same rank + 1 extra card (a Kicker);
  • Full House: 3 cards of the same rank + One Pair;
  • Flush: any 5 cards of the same rank (unordered);
  • Straight: any 5 cards in a row making up an ordered sequence, whatever their suits;
  • Three of a Kind: 3 cards of the same rank + any 2 other cards (Kickers);
  • Two Pair: 2 different pairs of same-ranked cards + 1 extra card (a Kicker);
  • One Pair: 2 cards of the same rank + any 3 other cards (Kickers);
  • High Card: any 1 card of the highest rank + any 4 other cards (Kickers).
 
In the case with 2 or more players obtaining same-ranking hands, the winner is determined by the Kicker card that is the highest remaining "spare" after putting together hands. 
 
It is possible that 2 or more players will have not just same-ranking hands, but same-ranking Kickers across them, too; in that case, the pot is split evenly between these players.
 

Game Stages, Or Rounds

Each game involves a number of subsequent rounds, each with its own specifics. Let's find out a bit more about each of them!
  1. Preflop: each player is dealt 4 cards, and the first betting round takes place;
  2. Flop: the first 3 community cards are revealed/turned face up, followed by the 2nd betting round;
  3. Turn: the 4th community card is revealed, followed by the 3rd betting round;
  4. River: the 5th and final community card is revealed, followed by the final betting round;
  5. Showdown: all the players that have made it to this round show their cards and determine the winner (or winners).
  

Player Moves

During betting rounds, players make, call or raise bets; they can also choose to fold. It is this very decision whether to fold or call a bet that determines one's success in poker.
 
Here are the types of bets you can pick from:
  • A blind bet is one that a player must make before they even get dealt their cards. Players take turns making blind bets from game to game. There is a Big and a Small Blind. The actual size, or value, of a blind depends on the table and, in fact, acts as a great way of estimating other potential bets and the potential pot size.
  • A bet is the first bet in a round, and it is available when nobody has yet made any bets in this round. The minimum bet size equals the size of the big blind, and there's no cap on the maximum bet size.
  • A raise is an increase of a bet, and it is available when at least one player has already made a regular bet in this round. This is quite an aggressive move, and it is justified in the case when a player is very confident about their hand OR if the player is bluffing. The minimum raise size depends of the previously made bet, and there's no cap the maximum raise size.
  • An all-in is a bet that equals the entire stack remaining at a player's disposal. If a player goes all-in, it is possible that a side pot will need to be set aside, which will happen if any other player responds with an even greater bet that exceeds the stack of the "all-inner".
Other move options:  
  • A call is responding to the highest bet made in this round so far with a bet of identical size.   
  • A check is available when a player's bet is already equal to the maximum bet made in this round.
  • A fold is ending one's current and further participation in the ongoing betting round, thus forfeiting one's chances to claim any winnings. Skilled players do not hesitate to fold when they see fit; knowing when to fold and not proceed is just as important as knowing when to bet on.