This is an unusually severe case. Warts are caused by a virus infection. The warts on the toes in this photograph are typical of warts on the feet. A person can spread warts from one location on the body to another by a process called autoinoculation. Warts are caused by a virus infection.
Children often develop small, flat warts on the face.
There are frequently hundreds of small individual warts present, giving the skin a rough look. They are difficult to treat without scarring, but left alone, they generally clear spontaneously after a few years. Warts are caused by a virus infection. Many products can be used in attempting to remove warts. This does not slough-off like normal skin cells.