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. Shoes are attached on the palmar surface (ground side) of the hooves, usually nailed through the insensitive hoof wall that is anatomically akin to the human toenail, although much larger and thicker. However, there are also cases where shoes are 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 others, 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 aluminium, 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. Aluminium shoes are lighter, making them common in horse racing, where a lighter shoe is desired; and often facilitate certain types of movement, and so are favored in the discipline of dressage. Some horseshoes have "caulkins", "caulks", or "calks": protrusions at the toe or heels of the shoe, or both, to provide additional traction.
When kept as a talisman, a horseshoe is said to bring good luck. Some believe that to hang it with the ends pointing upwards is good luck as it acts as a storage container of sorts for any good luck that happens to be floating by, whereas to hang it with the ends pointing down, is bad luck as all the good luck will fall out. Others believe that the horseshoe should be hung the other way (with the ends pointing down), as it will then release its luck to the people around it. A stylized variation of the horseshoe is used for a popular throwing game, horseshoes.