Warts are non-cancerous skin growths caused by a viral infection in the top layer of the skin.
Warts are usually skin-colored and feel rough to the touch, but they can be dark, flat and smooth.
The appearance of a wart depends on where it is growing. Flat warts Common warts - usually grow on the fingers, around the nails and on the backs of the hands. They are more common where skin has been broken, for example where fingernails are bitten or hangnails picked. When plantar warts grow in clusters they are known as mosaic warts. Most plantar warts do not stick up above the surface like common warts because the pressure of walking flattens them and pushes them back into the skin.