Brazilian Jiu-Jitsu (BJJ) is a martial art and combat sport that originated in Brazil. It focuses on grappling and ground fighting techniques, with an emphasis on leverage, technique, and strategy rather than relying on strength and size alone. BJJ was developed from Japanese Jiu-Jitsu by the Gracie family in the early 20th century.

One of the defining principles of BJJ is the concept that a smaller, weaker individual can defend themselves and defeat a larger, stronger opponent through proper technique, leverage, and submissions. BJJ practitioners aim to gain a dominant position on the ground, such as mount or back control, and then apply joint locks or chokes to force their opponent to submit.

Training in BJJ typically involves practicing techniques, drilling positions and transitions, and engaging in live sparring sessions (known as rolling or rolling sessions) to apply techniques in a realistic setting. BJJ is often utilized in mixed martial arts (MMA) competitions, as well as in self-defense situations.

BJJ promotes physical fitness, mental discipline, problem-solving skills, and self-confidence. It is practiced by individuals of various ages and genders, from recreational practitioners to competitive athletes. Belt rankings, starting from white and progressing to black belt, signify an individual's level of proficiency and knowledge in BJJ.

It's important to note that BJJ academies and instructors may have variations in training methodologies and approaches, but the core principles of leverage, technique, and ground fighting remain consistent throughout the discipline.