The Ultimate Fighting Championship (UFC) is a Mixed Martial Arts promotion formed in The '90s by the Gracies. Practitioners of Brazilian Jiu-Jitsu, they saw this as the ultimate style of fighting, and held a tournament where they would face all comers to prove it. The competition was open to all comers, martial artists, boxers, wrestlers, sumo wrestlers, street fighters, martial artist wrestling street fighters, whoever felt they were up to the challenge. Royce Gracie, who used a variety of submission holds that fighters were not used to seeing, won three of the first four UFC championships. From here, it was apparent that being a black belt in a particular discipline was not going to cut the mustard, and so taking a page from Bruce Lee, competitors began training to become martial artist boxing sumo wrestling street fighters.
Because the sport was seen as inherently dangerous the UFC struggled in it's early years, despite the success of the sport and names like the Gracies, Ken Shamrock and Dan Severn, some of who would make a name in other arenas such as WWE. Then at the turn of the millennium Zuffa, backed by casino owners Frank and Lorenzo Fertitta, was formed, who purchased the UFC for $2,000,000 and reformed and restructured the event. In 2005 a real life television program was created, The Ultimate Fighter, where contenders would be trained by professionals and fight each other to earn the chance of a UFC contract, in a Mixed Martial Arts cross between Big Brother and American Idol.
The reemergence of the UFC saw a number of changes take place. Instead of a no holds barred fight, each contest is strictly controlled and regulated, with a boxing style points system being implemented, referees stopping a fight if it gets too rough or an opponent is too injured or cannot defend themselves during the signature ground and pounds, stepping in to restart a fight in a stalemate or if there is no real fighting, and generally acting in the best interests of the fighter's safety, leading some to claim that as dangerous as some think the sport is it is safer than boxing. Instead of a take on all comers tournament the fighters have been split into different weight divisions, with proper ranks and seeds to determine who is in contention for a title shot.
The style of fighting has also evolved. As well as fighters needing two (or more) disciplines in order to be considered competitive, mixed martial arts has evolved into it's own style of fighting. Typically this would come in the form of basic punches and kicks, elbows, knees, and grapples where opponents will try and take each other to the ground, where they will either go for some variation of a choke, armbar or leg lock, or simply try and beat the opponent into the ground. One of the iconic sights of the UFC is for a fighting to sit on top of their opponent and punch them in the head again and again. Of course each fighter's training and experience would come into play, utilizing different moves and methods of delivery for strikes and holds, but this is a basic rundown of UFC Mixed Martial Arts fighting.
Today the UFC is one of the largest sports brands in the world, with Forest Griffin, Chuck Liddell, Brock Lesnar, and especially Ronda Rousey and Conor McGregor becoming household names, driving merchandising, spawning video games and the initiating the slow acceptance of the UFC as a competitive sport. It has far and away exceeded the Gracie's wildest imaginations of success and enjoys the same media attention and fan support the WWE enjoyed a decade before.