From Wikipedia: “Brazilian Jiu-Jitsu 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 martialart of Kodokan judo (which itself is derived from Japanese Jujutsu; the name Brazilian Jiu Jitsu is an homage to this origin) 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 and mixed martial arts (MMA) competition or self defense.”
Rubens “Cobrinha” Charles (pictured above) is one of the premiere grapplers in the world. Here he competes against Shane Rice (below), a tough grappler in his own right. Check out this really cool video of Cobrinha in action at the 2008 World Championships.