A wart is a small, rough growth resembling a cauliflower or a solid blister. It typically occurs on humans' hands or feet but often in other locations. Warts are caused by a viral infection, specifically by one of the many types of human papillomavirus (HPV). There are as many as 10 varieties of warts. It is possible to get warts from others; they are contagious and usually enter the body in an area of broken skin.