Judo is a Japanese Martial Art born out of Ju-Jitsu. Its creator, Jigaro Kano, was born in 1860, and Kano became a master of several styles of Ju-Jitsu. As a child Jigaro Kano was sickly and weak. When Kano was 18 he enrolled in the Tenjin Shino-Ryu school of Ju-Jitsu.
Tenjin Shino-Ryu was a soft Martial Art, that contained Striking and Grappling techniques. After studying there he moved on to the Kito-Ryu school of Ju-Jitsu. This style of Ju-Jitsu was softer and emphasized Throwing. Kano also studied other forms of Ju-Jitsu such as Sekiguchi-Ryu and Seigo-Ryu. Fusen Ryu was a school of Ju-Jitsu that specialized in ground fighting.
From this style Kano developed the Ne Waza (Ground techniques).
It contained 3 divisions--areas---Katame Waza (joint locking), Shime Waza (Choking Techniques) and Osea Waza (holding techniques).
He had a desire to master all of these different styles techniques.
Around 1880 Kano started thinking about combining all of the best techniques of the various schools into one system that could create a physical education system to combine mental and physical skill.
And he believed that these techniques could be practiced as a sport, if the more dangerous ones were removed.
In 1882 he put together what he thought were the best of Ju-Jitsu's Throwing and Grappling techniques and removed the Atemi Waza (Atemi Waza was still practiced by the highest skilled) and Kano had a new sport version of Ju-Jitsu, called Kodokan Judo.
Judo means gentle way. It retained the Throws, Chokes, Jointlocks, and Pins of Ju-Jitsu.
Kano considered Judo to be another style of Ju-Jitsu and before World War II it was still widely called Ju-Jitsu, or Kano's Ju-Jitsu.
Jigaro Kano was not only an innovator, but also a great practicioner. When one high-ranking Judoka was asked what it was like to compete against Kano, he said it was like fighting an empty jacket.
Judo was the first Martial Art to have belt ranking systems. It became an Olympic sport in 1964, and is now practiced all over the world.