Warts are non-cancerous skin growths caused by a viral infection in the top layer of the skin and mucus membranes. Viruses that cause warts belong to a family called human papillomavirus (HPV)). Warts are usually skin colored and feel rough to the touch, but they can also be dark, flat or smooth.
There are several types of warts: common warts around nails on the fingers and toes, foot warts also called plantar warts on the bottoms or soles of the feet, and flat warts that are flat and sooth. Flat warts can grow in great numbers at one time and affect any part of the body.
Warts should be treated to avoid spreading to other body parts or other people. They are most commonly treated with salicylic acid, cryotherapy (freezing) or electrodesiccation (burning). Depending on the depth of the wart, several treatments may be required. For warts that are especially stubborn to treatment, bleomycin injections can be used.