Mixed martial arts rules

Most rule sets for mixed martial arts competitions have evolved since the creation of life vale tudo. As the knowledge about fighting techniques spread among fighters and spectators, it became clear that the original minimalist rule systems needed to be amended. As rules evolved and regulations added, different branches of mixed martial arts have emerged, with differences between the different rulesets dictating different strategies. Similarly, shoot wrestling organizations, such as Shooto, expanded their rulesets to integrate elements of vale tudo into their sport. However, for the most part, fighters accustomed to one rule set can easily acclimate to a different ruleset, as the basics of fighting remain largely the same.

The most prevalent rule set in the world being used currently is the Unified Rules of Mixed Martial Arts, adopted by all state athletic commissions in the United States that regulate mixed martial arts and is used most notably in the Ultimate Fighting Championship. The Unified Rules are the de facto rules for mixed martial arts in the United States, and have been adopted by other promotions and jurisdictions worldwide. Other notable sets include Shooto's, which were the first to mandate padded gloves, and Pride rules, after PRIDE Fighting Championships, which were also adopted by UFC

Some main motivations for these rule changes included:

Weight classes emerged when knowledge about submission holds spread. When more fighters became well-versed in submission techniques and avoiding submissions, differences in weight became a substantial factor.

Headbutts were prohibited because it was a technique that required little effort and could quickly turn the match into a bloody mess. Headbutting was common among wrestlers because their skill in takedowns allowed them to quickly transfer bouts to the ground where they could assault opponents with headbutts while not being required to alter their position.

Small, open-finger gloves were introduced to protect fists in punches while still allowing for effective grappling. Gloves were first mandatory in Japan's Shooto league, but are now mandatory in matches for nearly every promotion. Although some fighters may have well conditioned fists, others may not. The small bones in an unprotected and unconditioned fist are prone to break when it hits a torso or forehead with power. Gloves also reduce the occurrence of cuts (and stoppages due to cuts) and encourage fighters to use their hands for striking, both of which enable more captivating matches.

...
Wikipedia