A corn is caused by the buildup of hard, dead skin over an area of pressure or bony prominence. The hard skin is produced by special skin cells called keratinocytes, which are present throughout the entire epidermal layer of skin.
Corns are the body's attempt at protecting itself from friction or pressure, but unfortunately, the extra skin becomes a painful problem in many cases. They are often cone-like and most commonly found on toe joints.
You may have a corn if you have a small, round area of thickened skin over a toe joint.
Corns on the feet are often caused by friction and pressure from footwear as well as abnormal patterns of walking or repetitive activities (such as in sports).