Reindeer, known as caribou in North America, are deer in the genus Rangifer. There are several distinct species in the genus. They have a circumpolar distribution, and are native to the Arctic, sub-Arctic, tundra, boreal forest, and mountainous regions of northern Europe, Siberia, and North America. Reindeer occur in both migratory and sedentary populations, and their herd sizes vary greatly in different geographic regions.
Reindeer are unique among deer (Cervidae) in that females may have antlers, although the prevalence of antlered females varies by species. The tundra species are adapted for extreme cold, and some are adapted for long-distance migration.
Although some reindeer populations are secure, many are in decline. Some species are secure as a whole, but subspecies within them are considered vulnerable. Reindeer have been an important source of food, clothing and shelter for arctic people throughout history, and are still hunted today.