The Horse Equus ferus caballus

All horse breeds today are domestic or feral except for the only remaining wild horse species, Przewalski's (link below). Most or all of today's horse and pony breeds are descended from the Eurasian wild Tarpan, Equus ferus ferus, the last of which died in captivity in 1909.
The "wild" horse herds such as American Mustangs are descended from domestic stock introduced by Europeans to the Americas. When feral, horses generally live in large herds headed by a lead male (stallion). Sometimes only females (mares) and young (foals) are in the main herd, with bachelor stallions in a separate group.
Horse Palamino
Horse Dun with foal
Horse Lead stallion with mares and foals
Domestic horses and ponies are the same species with different breeds. Horses are generally defined as over 14.2 hands (a "hand" is 4 inches, measured to the horse's withers - shoulder top; 14.2 hands is 14 hands plus 2 inches = 58", nearly 1.5 metres), but this isn't always the case and there are dwarf horses and very large ponies.
Horse Arabian bay
Horse Shire
Horse White
Domestic horses perform a range of roles mainly based on riding, haulage or food. In western countries, horses are used for racing, riding by military/law enforcement/public, agriculture, heavy transport and household pets. In Central Asia, they are farmed for meat and milk like cattle.
Piebald Horse Piebald (Skewbald)
Chestnut Horse Chestnut
Black and Grey Horses Black and Grey
While their wild ancestors were typically a light dun colour with a dark mane, tail and dorsal stripe, domestic horses come in a range of brown and grey colours including black, white, dappled grey, roan, dun, bay, palamino, chestnut, dark brown and mixtures of these.
Herd of Horses
Herd of HorsesHorses