Summarize this article in one sentence.
The most common cause of corns and calluses on the feet is something causing irritation, pressure, or friction in the same spot. By eliminating the source of the friction, you can prevent corns and calluses from forming. Shoes that do not fit can rub against your toes or cause your foot to slide inside the shoe.  Be sure your toes have plenty of wiggle room inside your shoes.  Corns develop along the tops and sides of your toes, and can be due to wearing shoes that do not give your toes enough room.  Repeated rubbing or irritation caused by shoes that do not fit properly are a major cause of corns of calluses.  Tightly fitting shoes and shoes with high heels that cause your fit to slide forward can cause corns and calluses to develop.  Calluses develop when the bottom or side of the foot slides against a part of the shoe that is irritating, or slides inside of shoes that are too large. Going without socks can cause your feet to experience friction and pressure from your shoes.  Always wear socks to prevent the friction and pressure. Especially in shoes that are designed to wear socks, such as athletic foot wear, heavy work shoes, and boots.  Be sure your socks fit properly. Socks that are too tight can squeeze your toes causing unwanted pressure and friction. Loosely fitting socks can slide down on your foot while in the shoe and contribute to added friction and pressure on areas of your foot. Use pads placed on top of the areas where the corns develop, between your toes, or along areas where the calluses form. Using pads, sections lamb’s wool, or toe separators can help to reduce the friction and pressure along your toe or foot area where the corns and calluses are located. Calluses form on your hands at the areas of greatest friction.  In many cases, calluses on the hand are welcomed. One example involves people that play musical instruments. Guitar players, for instance, appreciate the calluses that form on the tips of their fingers. This helps them to play their instrument without pain.  Another example is athletes that lift weights. The calluses that form on their hands can help them to grasp and manipulate the bars used in weight lifting.

Summary:
Eliminate the source of friction. Wear shoes that fit properly. Wear socks. Apply protective coverings. Wear gloves.