Cupping is an Acupuncture modality that uses glass or plastic cups over a muscle to create suction in that area. Usually a vacuum is created using a pump or a tiny flame (not near the skin) which seals the cup to the muscle.
Cupping can be super relaxing.
Much like a massage, but using suction instead of pressure. The suction from the cup encourages a high amount of blood flow to the area while creating micro tears in the tissues (not painful at all). When a tissue is saturated with blood flow it heals more quickly and more loose then it was previous to treatment. The idea is to loosen any tense muscles and create relaxation in inflamed tissues- thus reducing pain and encouraging faster healing.
There are some occasions and locations where cupping could be contraindicated so always see a licensed Acupuncturist for treatment.
Often the cups cause bruising- in China it is said that the more you bruise the more you needed it.
Because of the way that cupping encourages blood usage around the body it also detoxes the system a little. Cupping on the upper back can also help loosen sticky phlegm in the lungs- this can cause coughing until the mucous is fully expelled.
Cupping is often used to combat cellulite by loosening the fascia and connective tissue layer that surrounds muscle and fat and can cause cellulite.