A horseshoe, is a fabricated product, normally made of metal, although sometimes made partially or wholly of modern synthetic materials, designed to protect a horse's hoof from wear and tear. Shoes are attached on the palmar surface of the hooves, usually nailed through the insensitive hoof wall that is anatomically akin to the human toenail, though much larger and thicker. However, there are many cases where shoes are sometimes glued.

The fitting of horseshoes is a professional occupation, conducted by a farrier, who specializes in the preparation of feet, assessing potential lameness issues, and fitting appropriate shoes, including remedial features where required. In some countries, such as the United Kingdom, horseshoeing is legally restricted to only people with specific qualifications and experience. In other nations, such as the United States, where professional licensing is not legally required, professional organizations provide certification programs that publicly identify qualified individuals.

Horseshoes are available in a wide variety of materials and styles, developed for different types of horse and for the work they do. The most common materials are steel and aluminum, but specialized shoes may include use of rubber, plastic, magnesium, titanium, or copper. Steel tends to be preferred in sports where a strong, long-wearing shoe is needed, such as polo, eventing, show jumping, and western riding events. Aluminum shoes are lighter, making them common in horse racing, where a lighter shoe is desired; and often facilitate certain types of desired movement, and so are favored in the discipline of dressage. Some horseshoes have "caulkins", "caulks", or "calks": protrusions at the toe and/or heels of the shoe, to provide additional traction.