Corn and Callus What Is It? Corns and calluses are a thickening
of the outer layer of skin. This thickening is known medically
as hyperkeratosis. Corns and calluses develop as part of the
skin's normal defense against prolonged rubbing, pressure and
other forms of local irritation. - Corns. A corn is a protective
thickening of the skin on a bony, knobby portion of a toe. At
the center of a corn is often a very dense knot of skin called a
core, which is located over the area of greatest friction or
pressure. Firm, dry corns that form on the upper surfaces of the
toes are called hard corns. Pliable, moist corns that form
between the toes are called soft corns. In most cases, corns
develop when the foot has been squeezed into a shoe that has a
very narrow toe area. Less often, corns develop on deformed toes
that cannot fit comfortably into regular shoes. - Calluses. A
callus is a thickening of skin that is exposed to prolonged
rubbing. Unlike a corn, the thickening in a callus is evenly
distributed. There is no