Judo originates from the Japanese martial art jujutsu. Judo itself would later give rise to many variants, including Brazilian jiu-jitsu. Despite their common origins, however, each of the different martial arts derived from jujutsu varies in fundamental ways.
In many ways, judo and its descendant sports bear the hallmark of their progenitor art. Jujutsu had its origins in the constant fighting in Feudal Japan. The grapples and throws were among the most effective ways that Samurai warriors could pin down and incapacitate an armed or armored opponent without relying on a weapon.
Judo represents a refinement of these original techniques, relying on turning the opponent’s own force and momentum against them. Much like its predecessors, judo also focused on getting the opponent pinned down, with the understanding that the battle is over once the opponent is on the ground. This makes judo an excellent martial art to learn for self-defense and can be practiced largely noncompetitively.
The sport aspect of judo was later intensified in Brazilian jiu-jitsu, which focused heavily on achieving victory over an opponent and using every move to that end. Throws are worth points based on execution but do not finish the battle. Unlike judo, where fighters must stand back up when no fighters can remain on the ground until a submission hold is accomplished.
As a result, it is far more competitive than its predecessor and can be more prone to injury, although observers would note that it looks remarkably less violent than the faster-paced Judo.