Description: Warts are non-cancerous (benign) skin growths. The most common warts are warts that occur on the bottom of the feet (plantar warts), on the hands, and in the genital area (condyloma). When numerous warts come out in small clumps, they are called mosaic warts. When they occur under a fingernail or toenail, they are called periungual warts. They usually grow on the outer or horny layer of the skin otherwise known as the epidermis. Warts are not very serious, but they can be uncomfortable.