Corns and calluses form on the skin because of repeated pressure or friction. A corn is a small, tender area of thickened skin that occurs on the top or side of a toe. A callus is a rough, thickened area of skin that appears because of repeated irritation or pressure to an area of skin. Calluses usually develop on the palms of the hand and soles of the feet.
Review Date: 4/16/2013 Reviewed By: C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.