Cupping is an ancient Chinese practice in which a glass cup is applied to the skin through pressure changes inside the cup. This is performed by briefly heating the air inside the cup with the use of a flame, then quickly applying it to the skin. As the air inside the cup cools, a suctioning effect takes place pulling the skin and superficial muscle layer into the cup. Generally, several cups at a time are used and left in place for up to 20 minutes. During this process the skin will become temporarily red due to the congestion of blood flow inside. Cupping can be used to aide the treatment of back, neck, shoulder and other musculoskeletal pains by creating long lasting relaxation of the tissues and by reducing inflammation.