Threading is an ancient form of hair removal that is practiced in parts of Asia. It requires a technician to hold one end of a long cotton thread in her mouth and the other end with her hands to manipulate a loop. The loop is then formed around the base of each hair and tightened so the hair can be pulled out one at a time by the root. Lasting approximately two to four weeks, this method is best used on small areas like eyebrows and upper lip.