Description
Mixed martial arts (MMA) is a combat sport in which two competitors attempt to achieve dominance over one another by utilizing a wide variety of permitted martial arts techniques, including striking and grappling. Well-known MMA organizations include the Ultimate Fighting Championship and Pride Fighting Championships The techniques utilized in MMA competition generally fall into two categories: striking techniques (such as kicks, knees and punches) and grappling techniques (such as clinch holds, pinning holds, submission holds, sweeps, takedowns and throws). Some unarmed hand to hand combat techniques are considered illegal in arguably all modern MMA competition, such as biting, eye-gouging, fish-hooking and small joint manipulation. Over the last ten years strikes to the groin have become illegal in all legally sanctioned MMA organizations. The legality of other techniques such as elbows, headbutts and spinal locks vary according to competition or organization. Victory is normally gained through knockout, a submission, a stoppage by the referee or the fight doctor (in the event that the competitor is injured or can no longer defend themself intelligently), by a competitor's cornerman (throwing in the towel), or by judges' decision after an allotted amount of time has elapsed.

History
Modern mixed martial arts are rooted in two interconnected movements. First were the vale tudo events in Brazil, followed by the Japanese shoot wrestling shows. Vale tudo te(meaning 'anything goes') began in the 1920s with the famous "Gracie challenge" issued by Carlos Gracie and Hélio Gracie and upheld later on by descendents of the gracie family.[1] In Japan in the 1970s, a series of mixed martial arts matches were hosted by Antonio Inoki, inspiring the s hoot-style movement in Japanese professional wrestling, which eventually lead to the formation of the first mixed martial arts organizations such as Shooto.[4] Mixed martial arts gained real international exposure and widespread publicity in the U.S in 1993, when Royce Gracie won the first Ultimate Fighting Championship, sparking a revolution in the martial arts.[5] In 1994, Frederico Lapenda became the first non-Japanese to promote a mixed martial arts event in Japan, the Vale Tudo Championship.[1] In Japan in 1997, the continued interest in the sport eventually resulted in the creation of the PRIDE Fighting Championships.[6]

Rules variations
Each organization determines its own rules. Below are some of the significant differences in the rules of the popular MMA organizations.

Ultimate Fighting Championship
. Allows elbow strikes except ones starting from the twelve o'clock position and striking down to the six o'clock position.
. Prohibits spiking a fighter on the head during a takedown or slam.
. Prohibits stomps, soccer kicks and knees to the head of a grounded opponent (more than feet touching ground). A fighter on the ground can kick   upwards at their opponent's head only if their opponent is standing.
. Prohibits grabbing the fence with your fingers to control either your body position or your opponent's. You can put your hands on the fence, as well   as push off of the fence, but you are not allowed to use your fingers to grasp the fencing. The first offense is a verbal warning to let go. If the fence   is still held then the referee will tap the hand to physically remind the fighter to release. If that doesn't work, a foul is issued.
. Prohibits shoes, shirts and pants. Only boxing-styled shorts and padded MMA gloves are allowed.
. Uses three 5-minute rounds. Championship bouts are five 5-minute rounds.
. Matches scored through the 10-point must system
. NSAC does not allow the earlier single-event tournament format.
. Consists of five weight classes: Heavyweight (<265 lb), Light Heavyweight (<205 lb), Middleweight (<185 lb), Welterweight (<170 lb) and   Lightweight (<155 lb).
. Tests fighters for steroids and other illegal substances in championship bouts.

PRIDE Fighting Championships
. Uses a 10-minute first round with 5-minute second and third rounds.
. Prohibits elbow strikes to the head.
. Allows stomps, soccer kicks and knees to the head of a grounded opponent.
. No purposely holding the ropes. Fighters cannot purposely hang an arm or leg on the ropes. Hanging on the ropes will result in an immediate   warning.
. If fighters commit the following actions, they shall be given a yellow card by officials: Stalling or failure to initiate any offensive attack, making no   attempt to finalize the match or damage the opponent, and holding the opponent's body with the arms and legs to produce a stalemate. A yellow   card results in a 10% deduction/fine of the fighter's fight purse. A major difference in the penalty card system between PRIDE FC and BUSHIDO is   that in PRIDE FC a total of three yellow cards results in a red card (disqualification), while in BUSHIDO yellow cards can be given out in an   unlimited number without disqualification
. Uses tournament format to award Grand Prix champions.
. Has two weight classes: Heavyweight (no limit), and Middleweight (<92 kg).
. "BUSHIDO" event series consists of Lightweight (<73 kg) and Welterweight (<83 kg) fighters.

K-1 HERO's
. Uses two 5-minute rounds, with an extra round option should the judges be unable to determine a clear winner of the fight.
. Prohibits elbow strikes to the head, kicking by a fighter in the standing position to the face and head of a fighter in the ground position (When both   fighters are in the ground position, kicking to the face and head of the opponent fighter is allowed). Knee kicking to the face and head of a fighter   in the state of any ground position including 4-point position etc. is also illegal.
. Weight classes are currently being established. Lightweight is under 75 kg, others to be announced shortly.
. Has moved to a tournament format similar to that seen in K-1, with an eight man tournament. However, the final matches are not decided on the   same evening, but at later events. It is unsure if this format will become the standard at this time.

ZST
. Uses two 5-minute rounds.
. Does not use judges. The fight is declared a draw if there is no KO, TKO, Submission.
. Allows elbow and knee strikes only if they are covered by padding.
. Does not allow attacking head with strikes when one fighter is in downed position.

Shooto
. Uses A, B, and C levels. The C level is considered for amateurs only.
. Every level has its own rules and restrictions.
. The C level rules require headgear to be worn and prohibit striking on the ground.
. In case of a knockdown (when any part of a competitor's body touches the mat solely as the result of a strike) the referee will perform a 10-count.   The competitor has until the count of 10 to return to a standing position. Three knock downs in a single round will end the bout. There is also a   mandatory standing 8-count.

International Fight League
. Uses three 4-minute rounds.
. Fighters use different gloves ( Compared to other organizations) that have more padding.
. Fighters are divided into teams. Each team consists of five fighters, one representing each weight division of the International Fight League   (lightweight, welterweight, middleweight, light-heavyweight and heavyweight), and one head coach.
. Prohibits elbow strikes to the head, as well as stomps, soccer kicks and knees to the head of a grounded opponent.

Cage or ring
MMA is often referred to as "cagefighting" in the US as it is associated with the UFC's octagonal caged fighting area. Most major MMA promotions in the US, Canada and Britain use the "cage" as a result of directly evolving from the first UFC events. There are variations on the cage such as replacing the metal fencing with a net, or using a different shape for the area other than an octagon, which has been trademarked by UFC. In Japan, Brazil and some European countries such as Netherlands an area similar to a standard boxing ring is used, but with tighter ropes and sometimes a barrier underneath the lowest rope to keep grappling athletes from rolling out of the ring. The usage of the ring in these countries is derived from the history of Vale Tudo, Japanese pro-wrestling and other MMA related sports such as kickboxing. The choice of cage or ring is more than aesthetic however, as it impacts the type of strategies that a fighter can implement. For example, a popular and effective strategy in a cage is to pin an opponent into the area where the fence meets the mat, and then pummel him with strikes. This is not possible in a roped ring. On the other hand, the roped ring can result in entangled limbs and fighters falling through the ropes, requiring the referee to sometimes stop the fight and reposition the fighters in the center. Some critics feel that the appearance of fighting in a cage contributes to a negative image of MMA in popular media.