Texas Hold 'Em: If you have not heard of this type of poker, then chances are you have been living under a rock somewhere! Texas Hold 'Em is by far the most popular version of poker worldwide in today's world simply because of how easy it is for people to understand its rules. In Texas Hold 'Em, everyone is dealt two cards face down and then over the course of several betting rounds, five cards are dealt face up to the center of the table. These cards are community cards and can be used by everyone in conjunction with their own two cards in order to make the best five card poker hand.
Omaha: Omaha is a lot like Texas Hold 'Em, except instead of getting dealt two cards face down each player is dealt four cards face down. The other major difference is that in Omaha your five card poker hand must come about as a result of exactly two cards from your hand and three cards of the five community cards face up in the center of the table.
Omaha/8: Also known sometimes as Omaha Hi/Lo, this is a version of Omaha where the highest hand and the lowest hand split the spot. Qualifying low hands need to be at least an eight low or better and Omaha/8 is almost always played with A-5 (i.e. the wheel) being the lowest hand and no flush penalty.
7-Card Stud: Players start with two cards face down and one card face up. Over the course of the game, players are then dealt three more cards face up and one more card face down, with a betting round commencing after each successive card is dealt. The player that is able to form the best five card poker hand from the seven cards they are dealt is the winner of the pot.
7-Card Stud/8: Also sometimes referred to as 7-Card Stud Hi/Lo, the game is played in exactly the same manner as 7-Card Stud, but with the major difference that half the pot is won by the high hand and half the pot is won by the low hand, provided that there is at least one low hand that is eight low or better. As with Omaha/8, 7-Card Stud/8 is almost always played with the wheel being the lowest hand you can make and no penalties for a flush.
Razz: Razz is played in the exact same way as 7-Card Stud, except that the best hand is the lowest hand. There is no requirement for a hand to be eight low or better to qualify as a low hand and depending on the type of Razz, different hands are considered the lowest hand. There can be A-5 Razz (the most common kind), where the wheel low is the lowest hand. There can also be A-6 Razz (the least common kind), where aces are high or low and flushes and straights count (making the lowest hand A-2-3-4-6). And finally, there can be 2-7 Razz (somewhere in between and previously the most common kind), where aces are high and flushes and straights count (making the lowest hand 2-3-4-5-7).