Elk and other members of the deer family belong to a group of animals called ungulates, the Latin word for "hoof."
All ungulates have hooves.
This large group used to be considered one order, but now "ungulates" refers to two distinct orders, Artiodactyla and Perissodactyla.
The number of toes is the most obvious difference between the orders.
Artiodactyls (elk, deer, bison, pronghorn, peccary) have an even number of toes.
Perissodactyls (horses, elephants) have an odd number of toes.