Cupping therapy is a form of alternative medicine in which a local suction is created on the skin. Through suction, the skin is drawn into the cup by creating a vacuum in the cup placed on the skin over the targeted area. The vacuum can be created either by the heating and subsequent cooling of the air in the cup, or via a mechanical pump. The cup is usually left in place for somewhere between five and fifteen minutes. It is believed by some to help treat pain, deep scar tissues in the muscles and connective tissue, muscle knots, and swelling.