This is a martial art, a combat sport, and a system of personal defence derived from the techniques of judo and Jiu-Jitsu, imported into Brazil from Japan, by Mitsuyo Maeda, around 1920 then developed by the Gracie family.
Brazilian Jiu-Jitsu offers the concept that a person can defend itself against a heavier and stronger opponent, using appropriate techniques, more specifically in taking the fight to the ground and applying submission techniques; strangling, arm and leg locks, or muscular compression.
Intentional blows (strikes with feet, hands, elbows, head and knees) are forbidden in official practice.
This is a young martial art that is continually evolving and has as its essence, technique, timing and leverage, moreso than brute force.
It is traditionally practiced with a keikogi, often called a kimono, but with the particularity that it is tighter on the sleeves and legs, in order to make it harder to grab.
Jiu-Jitsu can be practiced by everybody.