Judo is a grappling martial art similar to jiu-jitsu, but does NOT involve punching or kicking.  Judo places emphasis on throws, pins, and submission holds such as strangles (+13 yrs only) and arm locks (+17 years only).  From a standing position involves techniques that allow you to lift and throw you or opponents onto their backs.  On the ground, it includes techniques that allow you to pin opponents down to the ground, control them and apply various choke holds or joint locks until submission.