Chi sau (sticking hands) is one of the most important aspects of Wing Chun. It is often confused with sparring and fighting. Chi sau is an outlet for a practitioner to test out what they have learnt in a live, ever changing environment. It is not fighting or sparring, but by the same token it is not a drill either. Chi sau trains sensitivity, reaction to an opponents movements, relative positioning, and footwork amongst others. In effect it is a laboratory in which a practitioner can try out ideas without the fear of being seriously injured.