Cupping applies suction to the surface of the body to draw out pathogenic factors or to invigorate the flow of Qi at the surface of the body.
Cupping is usually done by inserting a flame into a small glass cup to remove the air and create a vacuum. The cup is then deftly inverted onto the surface of the body where the cup is held firmly in place by the suction created by the vacuum effect. This method is called "fire cupping." There are also specially designed cups fitted with air lock valves that allow practitioners to remove the air with a hand-held pump.
Frequently, the practitioner will apply a lubricant to the skin before placing the cups, and then move the cups back and forth across certain area of the body. This combines the effects of cupping with dermal friction  therapy (gua sha) and is called "sliding cup" technique.
Cupping is frequently used to treat early stage colds and flu, trauma, and muscle pain , especially in the back and shoulders.
Cupping, like gua sha, leaves distinctive marks on the skin. While this is not harmful or painful, the markings are unsightly (resembling, as many patients describe them, "giant hickies and massive rug burns"). When cupping or gua sha is used on children, it is not uncommon for well-meaning child-care providers to mistake the markings as child abuse.
Understandably, TCM practitioners now provide their patients with informed consent information prior to the use of this therapy.