Ever wonder what causes corns and calluses? According to dermatologists from the American Academy of Dermatology, these hard, thickened areas of skin form as a result of friction or pressure on the skin. In fact, they say, corns and calluses develop naturally to help protect the skin underneath them. "Calluses can develop anywhere on the body where there is repeated friction, such as a guitar player's fingertips or a mechanic's palms," says board-certified dermatologist Nada Elbuluk, MD, FAAD, assistant professor of dermatology, NYU Langone Medical Center. "Corns typically develop on the tops and sides of the toes and on the balls of the feet, and common causes are arthritis or poorly-fitting shoes." Sometimes corns and calluses on the feet are mistaken for plantar warts, Elbuluk says, as they can look similar to the untrained eye. However, she says, if you look closely, you'll notice that plantar warts have tiny black dots within them. These dots are actually small blood vessels. In addition, plantar warts are typically more painful when pressure is applied to the sides of the warts, and corns and calluses are more painful under direct pressure. To treat corns and calluses, Elbuluk recommends the following tips: 1. Soak the corn or callus in warm water. Do this for about five to 10 minutes or until the skin softens. 2. File the corn or callus with a pumice stone. First dip the pumice stone in warm water, and then use the stone to gently file the corn or callus. Use circular or sideways motions to remove dead skin. 3. Be careful not to take off too much skin: Doing so could cause bleeding and infection. 4. Apply moisturizing lotion or cream to the area daily: Look for a moisturizing lotion or cream with salicylic acid, ammonium lactate, or urea. These ingredients will help gradually soften hard corns and calluses. 5. Use padding: To protect calluses from further irritation during activity, cut a piece of moleskin - available at your local drugstore - into two half-moon shapes and place around the callus. To prevent a corn from making contact with your shoe, surround the corn with donut-shaped adhesive pads - also available at drugstores. 6. Wear shoes that properly fit: A common cause of corns is a shoe that isn't the right size and shape for your foot. To get the right fit, shop for shoes at the end of the day, when your feet may be slightly swollen. In addition, ask a clerk to measure your foot, and choose shoes that aren't too loose or tight. 7. Keep your toenails trimmed: Toenails that are too long can force the toes to push up against your shoe, causing a corn to form over time. To remove this pressure, keep your toenails trimmed. "Most corns and calluses gradually go away when the friction or pressure causing them stops," says Elbuluk. "If you aren't sure what is causing your corn or callus, if the hardened skin is very painful, if you have diabetes, or if you think you have warts, see a board-certified dermatologist, podiatrist, or orthopedist."