Brazilian Jiu-Jitsu (BJJ) is a martial art and combat sport that focuses on grappling with the goal of gaining a dominant position, using joint-locks and chokeholds to force an opponent to submit.  The main emphasis in Brazilian Jiu-Jitsu is to dominate the opponent through application of technique and force them to quit (submit).  It promotes the principle that a smaller, weaker person using leverage and proper technique can successfully defend against a bigger, stronger assailant.
Brazilian Jiu-Jitsu can be trained for self-defense, sport grappling tournaments (gi and no-gi) and mixed martial arts (MMA) competition.  Sparring, commonly referred to as ‘rolling’, and live drilling play a major role in training.  By using the techniques of Brazilian Jiu-Jitsu, a smaller practitioner, male or female, can control much larger and stronger opponents and actually force the larger opponent to submit.   Jiu Jitsu literally translates to, "the gentle art." The philosophy is that not only can you, but that you actually should, learn to avoid the use of strength.  The individual should be able to obtain a position of dominance without using your strength, rather than necessarily immediately attempting to make the opponent submit. 

Rolker Gracie, Royler Gracie, Xande Ribeiro, Master Helio Gracie, Saulo Ribeiro