Equidae
Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, donkeys, and zebras, and many other species known only from fossils. All extant species are in the genus "Equus". Equidae belongs to the order Perissodactyla, which includes the extant tapirs and rhinoceros, and several extinct families.
Zebra
There are three species of zebras: the plains zebra, the mountain zebra and the Grévy's zebra. The plains zebra and the mountain zebra belong to the subgenus "Hippotigris", while Grévy's zebra is the sole species of subgenus "Dolichohippus". The latter resembles an ass, to which zebras are closely related, while the former two look more horse-like. All three belong to the genus "Equus", along with other living equids.