The
horse (
Equus ferus caballus) is one of two
extant subspecies of
Equus ferus. It is an
odd-toed ungulate mammal belonging to the taxonomic family
Equidae. The horse has
evolved over the past 45 to 55 million years from a small multi-toed creature,
Hyracotherium, into the large, single-toed animal of today. Humans began to
domesticate horses around 4000 BC, and their
domestication is believed to have been widespread by 3000 BC. Horses in the subspecies
caballus are domesticated, although some domesticated populations live in the wild as
feral horses. These feral populations are not true
wild horses, as this term is used to describe horses that have never been domesticated, such as the endangered
Przewalski's horse, a separate subspecies, and the only remaining true
wild horse. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from
anatomy to life stages, size,
colors,
markings,
breeds,
locomotion, and behavior.