Brazilian jiu-jitsu

(BJJ) is a martial art, combat sport, and a self defense system that focuses on grappling and especially ground fighting. The art was derived from the Japanese martial art of Kodokan judo (which itself is derived from Japanese Jujutsu) in the early 20th century.

It teaches that a smaller, weaker person can successfully defend against a bigger, stronger assailant by using leverage and proper technique – most notably by applying joint-locks and choke holds to defeat the other person. BJJ training can be used for sport grappling tournaments (gi and no-gi) and mixed martial arts (MMA) competition or self defense.[3] Sparring (commonly referred to as “rolling”) and live drilling play a major role in training, and a premium is placed on performance, especially in competition, in relation to progress and ascension through its ranking system.

http://en.wikipedia.org/wiki/Brazilian_Jiu-Jitsu