Chi Sau is a very special training method in Wing Chun. Apart from Taijiquan that has Tui Shou (Pushing Hands), basically no other styles of Kung Fu have such a developed method of partner training. Other styles may have something similar but much of that skill has been lost or it is quite simple. Most martial arts learn how to apply their skill through sparring and fighting each other. However, training like this will result in a lot of injury and this is not very good. Injuring ourselves before we need to defend ourselves does not make sense.
Chi means stick, Sau means hand – Sticking Hands. In Chi Sau two partners face each other and their hands contact or stick together and they attack and defend against each other. They start using basic hand techniques, Taan Sau 攤手, Bong Sau 膀手 and Fuk Sau 伏手. In Dan Chi Sau, Single Sticking Hands, there is Jum Sau 枕手 as well.
So Chi Sau is partner training where we learn how to use our Wing Chun techniques and improve our skill without hurting each other. We should remember that Chi Sau is not the same as fighting and so hurting our partners in Chi Sau is not a good thing.