All warts are caused by specific types of viruses that have an attraction for skin. They can grow on just about any part of the body. Their appearance depends on their location. Warts are slightly contagious and may spread from one part of the body to another or from one person to another.
Warts often resolve spontaneously without any treatment, especially in children. While the majority of warts can be successfully treated, some warts are extremely difficult to eradicate (especially those around the fingernails and on the bottom of the foot). Occasionally a wart may actually be a skin cancer so you should have all warts checked if they do not resolve within a month or two.
Warts can be treated with liquid nitrogen or with laser. Several treatments on the same wart are usually necessary to completely remove the wart.