It's an alphabet soup of blood, sweat and submissions. And with mixed-martial arts growing to unprecedented popularity, there has been an explosion in the number of promotions looking to cash in on the sport's new-found fame.
Here's a look at the biggest North American MMA promotions and their stars.
The reigning champion of MMA. The Ultimate Fighting Championship enjoys a rich history dating back to the first event in Denver in 1993. At that time, the rules of engagement were few enough to fit on a fast food napkin. Since then, the UFC has been instrumental in sanctioning the sport across the U.S. and developing unified rules followed by most legitimate fight clubs. It is credited with bringing the sport to a mainstream audience through its The Ultimate Fighter reality show. In 2007, UFC brass purchased its major competitor -- Japan's Pride Fighting Championship -- and absorbed most of its key fighters.
Big Stars: Randy 'The Natural' Couture, Georges 'Rush' St. Pierre, BJ 'The Prodigy' Penn, Forrest Griffin, Anderson 'Spider' Silva, Wanderlei Silva and Chuck 'The Iceman' Liddell.
Next Event: UFC 89 featuring Michael Bisping and Chris Leben
A monster in the world of T-shirts, Tom Atencio took his passion for MMA, teamed up with Donald Trump and more recently Oscar De La Hoya's Golden Boy promotions and set his sights square on the UFC's dominance of the sport. Its first event at Anaheim's Honda Centre in July featured a stacked card and a performace by Megadeth between bouts. Affliction has the man many consider the top pound-for-pound fighter on the planet -- Russia's Fedor Emelianenko -- in its stable. Affliction raised some eyebrows when it unveiled its fighter pay for the night showing even the the loser of the main event --Tim "The Maine-iac" Sylvia at $800,000 -- made more in purse money than any winning headliner in the UFC's history.
Big Stars: Emelianenko, Andrei 'The Pitbull' Arlovski, Josh 'Babyfaced Assassin' Barnett, Matt 'The Law' Lindland and Vitor 'The Phenom' Belfort.
Next event: Early January in Anaheim. Emelianenko expected to be on the card.
EliteXC has done one thing no other fight club has been able to do: Land a major network, prime-time contract to showcase its fights. The deal with CBS has the potential to give the fight club the largest exposure of any promotion.
But its last show failed to draw significant viewership and the fight club has come under fire for feeding stepping stones to its No. 1 figher -- former internet backyard brawler Kevin "Kimbo Slice" Ferguson.
Big Stars: Kimbo Slice, Robbie Lawler, Jake Shields, Gina Carano, Antonio Silva, KJ Noons and Nick Diaz.
Next event: October 4 on CBS. Main event features Kimbo Slice against Ken Shamrock.
The San Jose-based fight club is perhaps the least known of the big four, but once held the attendance record for most fans to a live event -- more than 18,000 people attended the Frank Shamrock vs. Cesar Gracie card in 2006. The fight club also put on one of the top fights of the year when Shamrock took on Cung Le in March.
With a new deal in hand with The Score, Canadian fight fans will become more familiar with Strikeforce.
Big Stars: Cung Le, Frank Shamrock, Gilbert Melendez and Josh Thomson,
Next event: Strikeforce at the Mansion goes tonight and is avalable in The Score.