(HealthDay News) -- Corns are thick calluses that form on the feet, and they can be quite painful.

The American Academy of Orthopaedic Surgeons lists these possible causes:

• Wearing shoes that are too tight and squeeze the feet.
• Wearing shoes that are too loose and allow the foot to slide around.
• Having a stitch or seam inside a shoe that rubs against the toes.
• Wearing socks that don't fit your feet well.
• Having a deformity of the toes, including a hammer toe or claw toe.