Brazilian Jiu-Jitsu is a martial art and combat sport that focuses on grappling and especially ground fighting. It is a derivative of early 20th century Kodokan Judo, which was itself then a recently-developed system (founded in 1882), based on multiple schools (or Ryu) of Japanese jujutsu.
It promotes the principle that a smaller, weaker person can successfully defend themselves against a bigger, stronger assailant using leverage and proper technique; most notably, by applying joint-locks and chokeholds to defeat them. BJJ 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, and a premium is placed on performance, especially in competition.
Brazilian Jiu-Jitsu came to international prominence in the martial arts community in the 1990s, when Brazilian Jiu-Jitsu expert Royce Gracie won the first, second and fourth Ultimate Fighting Championships, which at the time were single elimination martial arts tournaments. Royce fought against often much-larger opponents who were practicing other styles, including boxing, shoot-fighting, karate, judo, tae kwon do and wrestling. It has since become a staple art for many MMA fighters and is largely credited for bringing widespread attention to the importance of ground fighting. Sport BJJ tournaments continue to grow in popularity worldwide and have given rise to no-gi submission grappling tournaments, such as the ADCC Submission Wrestling World Championship.