Warts are caused by the human papillomavirus (HPV) and are contagious when in contact with the skin of an infected person. It is also possible to get warts from using towels or other objects used by an infected person. Common warts grow on your hands or fingers. Treatment helps prevent common warts from spreading to other parts of your body or to other people. Unfortunately, they may recur after treatment, and they may be a persistent problem. See your doctor if the warts persist,or becomes painful or rapidly multiplying. You can read more about this through this link: http://en.wikipedia.org/wiki/Wart