In Kodokan Judo there are two ways to train and practice the previos mention techniques, these being randori (free practice) and kata (forms).
In randori, you and your fellow judoka (judo player) move freely around the mat in an attempt to either throw your oppenet, or if you are practing graplling techniques then you try to apply a pin, a choke, or an armbar (jointlock). The advantage to practicing with this method is that you develop your ability to think and react quickly accordingly to what your opponet does.
In kata you and your fellow judoka are designated as either tori
(initiator) or as uke (reciever). Then tori and uke move together in a
predifined path during which tori applies a designated technique at a designated
point. The purpose of this type of practice is to allow you to understand the
exact way each technique is to be preformed and as a way for you to perfect each
technique. Note that atemi-waza is only practiced in kata for the safety of the judokas.
