Of all the many thousands of types and breeds of horses; they are all of the same above listed genus and species.

Furthermore, all feral horses and all wild horses are also the same: Equus ferus, but also of the same sub-species caballus, which means that at some time, all of them were domesticated horses and later became feral and/or wild. This is despite whether feral horses were born and/or live in the wild, all are descended from domesticated animals.

There are many populations of feral horses that exist throughout the world. Further, there have been some studies of feral herds and these studies have provided useful insights into the behavior of prehistoric horses, as well as greater understanding of the instincts and behaviors that drive horses that live in domesticated conditions.

However, within the species of E. ferus, there are three accepted sub-species.

The horse is an odd-toed ungulate mammal belonging to the family Equidae is one of two extant subspecies of Equus ferus. Humans began to domesticate horses around 4000 BCE, 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. A person could spend years learning all these concepts. Rather, the study contained on these pages will not endeavor to examine all of them but will touch on only a few.

Colt: A male horse under the age of four. A common terminology error is to call any young horse a "colt", when the term actually only refers to young male horses.

Filly: A female horse under the age of four.

Foal: A horse of either sex less than one year old. A nursing foal is sometimes called a suckling and a foal that has been weaned is called a weanling. Most domesticated foals are weaned at five to seven months of age, although foals can be weaned at four months with no adverse physical effects.

Gelding: A castrated male horse of any age.

Mare: A female horse four years old and older.

Stallion: A non-castrated male horse four years old and older. The term horse is sometimes used colloquially to refer specifically to a stallion.

Yearling: A horse of either sex that is between one and two years old.

Female horses, called mares, carry their young for approximately 11 months, and a young horse, called a foal, can stand and run shortly following birth. Most domesticated horses begin training under saddle or in harness between the ages of two and four. They reach full adult development by age five, and have an average lifespan of between 25 and 30 years.

There are more than 300 breeds of horse in the world today, developed for many different uses. Horse breeds are loosely divided into three categories based on general temperament:

1. Spirited hot bloods with speed and endurance;

2. Cold bloods, draft horses and ponies, suitable for slow, heavy work; and

3. Warm bloods, by crossing hot and cold bloods, for specific riding purposes.

The height of horses is usually measured at the highest point of the withers, where the neck meets the back, which is used because it is a stable point of the anatomy, unlike the head or neck, which move up and down in relation to the body of the horse.

In English-speaking countries, the height of horses is often stated in units of hands and inches: one hand is equal to 4 inches. The height is expressed as the number of full hands, followed by a point, then the number of additional inches, and ending with the abbreviation "h" or "hh" (for "hands high"). Example: 15.2 h is 15 hands and 2 inches, for a total of 62 inches in height.

The size of horses varies by breed and by nutrition. Light riding horses usually range in height from 14 to 16 hands and can weigh from 840 to 1,210 pounds. Larger riding horses usually start at about 15.2 hands and often are as tall as 17 hands, weighing from 1,100 to 1,320 pounds. Heavy or draft horses are usually at least 16 hands high and can be as tall as 18 hands high, weighing from about 1,540 to 2,200 pounds.

Probably the most diverse equine study is this study of coat color, and it so diverse in descriptions, has many modifiers, markings and unique identifiers that for this writer, it will be a subject for the paradise. However, the following is just a few basics about the horse and it′s coat.

Most horses remain the same color throughout life, however, a few, over the course of several years, will develop a different coat color from that with which they were born. Most white markings are present at birth, and the underlying skin color of a horse does not change, except for cases caused by disease.

The basic outline of equine coat color genetics has largely been resolved, and DNA tests to determine the likelihood that a horse will have offspring of a given color have been developed for some colors. Discussion, research, and even controversy continues about some of the details, particularly those surrounding spotting patterns, color sub-shades such as "sooty" or "flaxen", and markings.

White markings are present at birth and unique to each horse, making them useful in identifying individual animals. Markings usually have pink skin underneath them, though some faint markings may not, and white hairs may extend past the area of underlying pink skin. Though markings that overlie dark skin may appear to change, the underlying skin color and hair growing from pink skin will not. Horses may also be uniquely identified by an unusual eye color, whorls, brands and chestnuts.

The Przewalski′s horse, also called: Khalkha Mongolian; Polish; or Dzungarian horse, is a rare and endangered subspecies of wild horse (Equus ferus) native to the steppes of central Asia. At one time extinct in the wild (in Mongolia, the last wild Przewalski′s horses had been seen in 1966), it has been reintroduced to its native habitat in Mongolia at the Khustain Nuruu National Park, Takhin Tal Nature Reserve, and Khomiin Tal. The taxonomic position is still debated, and some taxonomists treat Przewalski′s horse as a species, Equus przewalskii.

Wild horses today, such as the American mustang or the Australian brumby, are actually feral horses descended from domesticated animals that escaped and adapted to life in the wild. In contrast, the Przewalski′s horse has never been domesticated and remains the only true wild horse in the world today.

There are still a number of other wild equines, including three species of zebra and various subspecies of the African wild ass, onager (including the Mongolian wild ass), and kiang.

In the wild, Przewalski′s horses live in small, permanent family groups consisting of one adult stallion, one to three mares, and their common offspring. Offspring stay in the family group until they are no longer dependent, usually at two or three years old. Bachelor stallions, and sometimes old stallions, join bachelor groups. Family groups can join together to form a herd that moves together.

The native population declined in the 20th century due to a combination of factors, with the wild population in Mongolia dying out in the 1960s. The last herd was sighted in 1967 and the last individual horse in 1969. Expeditions after this failed to locate any horses, and the species had been designated "extinct in the wild" for over 30 years

After 1945 only two captive populations in zoos remained, in Munich and in Prague. The most valuable group, in Askania Nova, Ukraine, was shot by German soldiers during World War II occupation, and the group in the United States had died out. Competition with livestock, hunting, capture of foals for zoological collections, military activities, and harsh winters recorded in 1945, 1948 and 1956 are considered to be the main causes of the decline in the Przewalski′s wild horse population. By the end of the 1950s, only 12 individual Przewalski′s horses were left in the world

Every Przewalski horse presently living is descended from 9 of the 13 horses captured in 1945. Two of these were hybrids, one sired from a wild horse stallion and domestic mare and the other from a wild stallion and a tarpan mare. These 13 horses were descended in turn from approximately 15 captured around 1900.

A cooperative venture between the Zoological Society of London and Mongolian scientists has resulted in successful reintroduction of these horses from zoos into their natural habitat in Mongolia, and as of 2011 there is an estimated free-ranging population of over 300 in the wild.

From a population of 13 horses held in captivity in 1945, the total number by the early 1990′s was over 1,500. A population introduced in 1998 exists in the Chernobyl Exclusion Zone protected from interference by humans, and is thought to be increasing in size.

The tarpan (Equus ferus ferus), also known as Eurasian wild horse or simply, wild horse, was a subspecies of wild horse. It was a free-ranging horse that was of the Eurasian steppe from the 1700s to the 1900s and it is unknown whether these horses represented genuine wild horses, feral domestic horses or hybrids. The last individual believed to be of this subspecies died in captivity in Russia in 1909, although some sources claim that it was not a genuine wild horse due to its resemblance to domesticated horses, still, what ever it was, they are now extinct.

Beginning in the 1930s, several attempts were made to develop horses that looked like tarpans through selective breeding, called breeding back by advocates.

The breeds that resulted included the Heck horse, the Hegardt or Stroebel's horse, and a derivation of the Konik breed, all of which have a primitive appearance, particularly in having the grullo coat color. Some of these horses are now commercially promoted as tarpans, although such animals are only domestic breeds and not wild animals.

However, those who study the history of the ancient wild horse assert that the word "tarpan" only describes the true original wild horse.