A grade horse is a horse whose parentage is unknown, unidentifiable, or of significantly mixed breeding. This differs from purebred animals of known bloodlines and also differs from deliberately crossbred animals that are produced with an intent of either creating a new breed of horse or an animal with characteristics that deliberately combine the strengths of two different breeds. Many grade horses are the result of unintentional or accidental breedings, though in some cases, they are the result of a planned breeding of a stallion and a mare, but animals who themselves are of uncertain bloodlines. Some grade horses may have at least partially known breeding, but may not have been registered by their breeder, particularly if the product of an unintended mating, or may have been sold without papers. A horse that is registered is one recorded with a breed registry or stud book, having written documentation of its pedigree. A grade horse has no registration papers, and usually sells for significantly less money than a registered horse. However, some grade horses with special talent or a proven performance record in a given discipline may become valuable on their individual merit.