Brazilian Jiu-Jitsu (also known as Gracie Jiu-Jitsu and BJJ) is a ground fighting martial art that is based on early 20th century Kodokan Judo. It was developed and then refined through a series of Mixed Martial Arts competitions to become the most effective grappling method in the world. BJJ utilizes positional control and effective grappling techniques, including joint locks and choke holds, to force opponents into submission. Underlying all effective Jiu-Jitsu techniques is the concept of leverage. Mastery of this concept is what eliminates the impact of size and strength disparities in a confrontation.