warts are an infection of the skin caused by the human papillomavirus hpv the virus enters the body through a break in the skin such as a cut and then forms a rough bump on the surface of the skinwarts are benign non cancerous growthsarts are an infection of the skin caused by the human papillomavirus hpv the virus enters the body through a break in the skin such as a cut and then forms a rough bump on the surface of the skin