Brazilian Jiu-Jitsu (BJJ) is a martial art focusing on ground fighting and submission holds. It emphasizes the concept of leveraging smaller size and strength to defeat bigger and stronger opponents. Through technique and strategy, practitioners learn to apply joint locks and chokeholds to control or submit their opponent. BJJ training promotes the principle that a person can defend against an assailant by using technique and leverage rather than pure physical strength, making it an effective self-defense system for all ages and sizes.