Reindeer are a species of deer whose natural habitat is the far northern areas of arctic Europe, Asia, and North America extending onto the tundra above the tree-line . The name for these deer found native to North America (including Greenland) is "Caribou", while in Europe it is known as the "Reindeer". They are the same species. The reindeer is thought to have first been domesticated by humans at least 3,000 years ago (and perhaps as long as 7,000 years ago) in northern Eurasia (Lapland), and still remains the only deer to be widely domesticated. Used as beasts of burden and farmed for milk, meat and their hides, reindeer have been the economic basis of the Lapp culture for centuries. However, because of their popularity, today they are raised in many areas of the world outside of their native arctic.

• The fur coat consists of an outer layer of straight, hollow, tubular hairs which provide insulation from the cold and buoyancy in water, and a woolly under-coat. The coat is such an efficient insulator that when they lay on the snow, the snow does not melt.
• Coloration is variable, ranging from pure white through tan to dark brownish gray, with the undersides and rump lighter. The legs are generally dark, as is a band which runs along the lower torso. There is an area of loose skin (called a dewlap) on the throat covered with long white hair and the face is usually dark The facial hair protects its muzzle when grazing in snow.
• They are the only species of deer in which both male and female (and even calves) have antlers . Antlers are shed annually and new antler growth occurs in the spring and summer.
• The hoofs are very large and form a nearly circular print. They spread to aid when walking on soft ground and snow and are used to dig for food underneath snow.
  
• Adult males can weigh over 300 pounds and adult females can exceed 200 pounds. The shoulder height is generally around three to three-and-a-half feet for females and three-and-a-half to four feet for males. North American Caribou can be somewhat larger reaching a height of 55 inches and well over 400 pounds.
• In their natural habitat they eat leaves, herbs, lichens, sedges, and fungi, while in captivity they are fed a balanced diet of commercial grains, forage and supplements.
• Almost all reindeer in Europe and Asia are domesticated while in the North American arctic there are vast herds of wild Caribou that migrate great distances every year. One of the considerations when the Alaska Pipeline was built was that it could not be allowed to block the Caribou migrations. They are strong swimmers and can move across wide, rushing rivers and even venture across channels of the Arctic Ocean.