Razz poker is pretty much like 7-Card Stud, only it’s played with lows instead of highs. Winning hands are the worst poker hands, and the best Razz hand is the: As, 2h, 3d, 4c, 5s. Straights don’t count in Razz, and neither do Flushes.

The gameplay itself commences with every player posting an ante after which they’re dealt 2 cards face down (hole cards) and one face up (the door card). Before I forget: Razz is played as fixed limit only, so adjust your betting strategy to that if you play it.
The player who has the highest door card will go on to post the “bring-in”. Obviously everyone wants to avoid having to post the bring-in, so the lower your door card at this stage, the better off you are. When the two highest door-cards are of the same value, suit is used as tiebreaker. The highest suit is Spades, followed by hearts, diamonds and clubs. If you get a Ks (Kind of spades) as your door-card, you might as well break open the piggy-bank, as you’ll be “bringing it in” for sure. Play goes around clockwise (as it usually does in poker).

After the first betting round, players who still stick it out, get another door card (a face-up one). This time, the player holding the lowest hand (the best partial Razz hand) starts the betting. For this, only his two door cards are considered, of course.
The deal/betting round sequence goes on like this until the 5th card. Then the limit is doubled and the game goes on. The 7th card is dealt face down again, followed by the last betting round. At showdown, the player who can make the lowest 5 card hand out of the 7 cards dealt, is the winner.

Razz is pretty much available in every self respecting poker room (PokerStars, Full Tilt Poker, etc.). If you notice that a room offers H.O.R.S.E. you should know that the “R” in that name stands for Razz.