Classic acupuncture is the art of inserting fine, sterile, metal filiform needles into certain points along the channels and collaterals (tributaries of the channels) in order to control the flow of the Qi. Acupuncture is well-known for its effectiveness as a painkiller. Even more powerful is its ability to alter the flow of the Qi so that the body can heal itself when attacked by pathogens that trigger disharmony.