Brazilian Jiu-Jitsu is a martial art, combat sport, and a self defence system that focuses on grappling and especially ground fighting. The art was derived from the Japanese martial art of Kodokan judo 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 chokeholds to defeat the other person. Brazilian Jiu Jitsu training can be used for sport grappling tournaments (gi and no-gi) and mixed martial arts (MMA) competition or self defense. 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 the grades/belts.
If you are a fan of the UFC, there is a good chance you have already seen it in action! For many professional MMA fighters having an in depth understanding and knowledge of Jiu Jitsu is essential, many past & current MMA champions have a foundation in Jiu Jitsu and use it to regularly defeat their opponents. Being able to stand and fight is one thing, being able to take your opponent to the ground and win is another thing completely.
This video gives a nice brief history: