Mixed martial arts (MMA) is a form of competitive combat sport, akin to boxing, muay thai, or kick boxing. MMA titles, or championship belts, are given to those fighters deemed by a promotional organization to have met a certain standard of athletic accomplishment in a specific weight class (most often by means of a championship fight). Championship belts are fought for at each weight class under a promotion, with only one belt awarded per class. Each belt is usually contested every time the belt holder fights, and passed to the victor of that fight (see the List of UFC champions for a chronology of UFC title belts). A belt may be vacated when a fighter leaves a promotion, or is suspended. At such times an interim champion may be crowned, or the belt may be awarded to the winner of a fight