Warts are skin growths that are caused by the human papillomavirus (HPV). There are more than 60 kinds of HPV, some of which tend to cause warts on the skin. HPV stimulates quick growth of cells on the skin's outer layer.

There are many types of warts. Common warts appear on the fingers, around the fingernails, or on the hands. Plantar warts usually appear on the soles of the feet or on the toes. They often cause discomfort with walking. Another type includes flat warts which are small, flat and tend to appear in clusters. They typically appear on the face and on the back of the hands. The lower legs are also common areas, especially in women.


Because warts are caused by viruses, they can be slow to respond to treatment. Often, several treatments may be necessary to completely get rid of a wart. Sometimes a combination of different therapies is necessary for successful treatment.