A wart is caused by an infection of the human papilloma virus, medically categorized as common warts, plantar warts, and flat warts. These viral warts are contagious and can be passed on to other people under specific conditions. Common warts can occur on any part of the body, and it is possible for others to become infected when they have a break in their skin and come into contact with them. Flat warts occur on the face, backs of the hands and forearms, and are mostly contagious on their own, and may be transmitted when others share bath towels, washcloths and scrubbers. Plantar warts are found on the soles of the feet and can be transmitted to others when they share a pair of slippers or a footbath.