Cupping is a therapy in which a special cup or jar is attached to the skin by means of suction. The suction is created by heating the air inside the cup to create a vacuum, then quickly pressing the mouth of the cup to the desired area. In ancient times, it was done with bamboo cups or animal horns, and it was often employed to treat external conditions of the skin and muscles such as sprains and strains and drawing out pus. It is especially effective for musculoskeletal pain, often relieving the pain after a single application.The force of the suction draws stagnant blood to the surface of the body, sometimes leaving a round bruise in the shape of the cup. Since pain is caused by the stagnation of qi and blood, the goal of this therapy is to remove the stagnation, increase circulation, and allow healing to take place.