Corn is a small, hard, shiny thickening of the epidermis (outer layer of the skin). This thick growth presses on the dermis (deeper skin layer) and causes it to become thin and tender. Pressure and friction cause corns. Therefore, corns often develop over the joints of the toes of persons who wear shoes that do not fit properly. But corns may form anywhere on the body where pressure and friction injure the skin. A soft corn is one located between the toes. Here the thickened skin remains soft because it is constantly bathed with sweat.