The causes of Warts are various types of human papillomavirus (HPV). Some types of HPV are also known to cause cancer of the cervix (mouth of the uterus).
HPV infects the top layer of skin, usually entering the body in an area of broken skin. The virus causes the top layer of skin to grow rapidly, forming a wart. It can then spread from an existing wart to other areas of the body, causing more warts.