Common and plantar warts are non-cancerous skin growths caused by the human papillomavirus.
Warts can be round or irregular in shape, flat or raised from the surface of the skin. Typically, common warts grow around the nails, on the fingers and on the backs of hands, but also can be found on the knees and face (most often where the skin has been previously broken). A common wart can also be recognized by its rough, "cauliflower"-like surface.