Chi Sau is a very important part of Wing Chun. (Chi means 'Stick' and Sau means 'hands', together they mean 'Sticking Hands'.) You can almost say that if someone's Chi Sau is not good, their Wing Chun will not be good.
Students of Wing Chun need to develop sensitivity and correct skill, and this is why Sticking Hands is practised. It is an exercise in which people work in pairs to train their technique, position and sensitivity. It allows both partners to learn the basics of fighting skill without hurting each other. Both partners should be relaxed and should not try to hit each other. They should be focusing on their positioning and the correct use of energy.
-GM Ip Chun with GM Michael Tse
Photo; taken during the celebration of GM Ip Chun's 90th birthday (September 2013), shown here with GM Ip Chun is his Tou-Syun, Master Moy.