The name "wapiti" is derived from a Shawnee and Cree word meaning "white rump", after the distinctive light fur around the tail region which the animals may fluff-up or raise to signal their agitation or distress to one another, when fleeing perceived threats, or among males courting females and sparring for dominance.

Elk dwell in open forest and forest-edge habitats, grazing on grasses and sedges and browsing higher-growing plants, leaves, twigs and bark.

Elk were long believed to belong to a subspecies of the European red deer (Cervus elaphus), but evidence from many mitochondrial DNA genetic studies, beginning in 1998, shows that the two are distinct species.

The now-extinct North American Merriam's elk subspecies (Cervus canadensis merriami) once ranged south into Mexico.

As a member of the Artiodactyla order (and distant relative of the Bovidae), elk are susceptible to several infectious diseases which can be transmitted to or from domesticated livestock.

By the 8th century, during the Early Middle Ages, the moose was known as Old English: elch, elh, eolh, derived from the Proto-Germanic: *elho-, *elhon- and possibly connected with the Old Norse: elgr.

Richard Hakluyt refers to North America as a "lande ... full of many beastes, as redd dere"[8] in his 1584 Discourse Concerning Western Planting.

Sir William Talbot's 1672 English translation of John Lederer's Latin Discoveries likewise called the species "red deer", but noted in parentheses that they were "for their unusual largeness improperly termed Elks by ignorant people".

[13] Elk and red deer produce fertile offspring in captivity, and the two species have freely inter-bred in New Zealand's Fiordland National Park.

[15] There are numerous subspecies of elk described, with six from North America and four from Asia, although some taxonomists consider them different ecotypes or races of the same species (adapted to local environments through minor changes in appearance and behavior).

DNA investigations of the Eurasian subspecies revealed that phenotypic variation in antlers, mane and rump patch development are based on "climatic-related lifestyle factors".

[13] These Chinese subspecies are sometimes treated as a distinct species, namely the Central Asian red deer (Cervus hanglu), which also includes the Kashmir stag.

[22] The largest of the subspecies is the Roosevelt elk (C. c. roosevelti), found west of the Cascade Range in the U.S. states of California, Oregon and Washington, and in the Canadian province of British Columbia.

[31] Most have lighter yellow-brown to orange-brown coats in contrast to dark brown hair on the head, neck, and legs during the summer.

[42] As is true for many species of deer, especially those in mountainous regions, elk migrate into areas of higher altitude in the spring, following the retreating snows, and the opposite direction in the fall.

[45] During the spring and fall, they take part in the longest elk migration in the continental U.S., traveling as much as 168 mi (270 km) between summer and winter ranges.

[51][52] Research in the Greater Yellowstone Ecosystem has found that supplemental feeding of concentrated alfalfa pellets leads to significant alterations in the elks' microbiome.

Large bull elk are less vulnerable and can afford to wander alone, while cows stay in larger groups for protection for their calves.

Parelaphostrongylus tenuis (brainworm or meningeal worm) is a parasitic nematode known to affect the spinal cord and brain tissue of elk and other species, leading to death.

[65] The liver fluke Fascioloides magna and the nematode Dictyocaulus viviparus are also commonly found parasites that can be fatal to elk.

[66] Chronic wasting disease, transmitted by a misfolded protein known as a prion, affects the brain tissue in elk, and has been detected throughout their range in North America.

First documented in the late 1960s in mule deer, the disease has affected elk on game farms and in the wild in a number of regions.

[67] In 2002, South Korea banned the importation of elk antler velvet due to concerns about chronic wasting disease.

[72] Elk hoof disease was first noticed in the state of Washington in the late 1990s in the Cowlitz River basin, with sporadic reports of deformed hooves.

Relictual populations survived into the early Holocene (until around 3000 years ago) in southern Sweden and the Alps, where the environment remained favorable.

[76] Elk were also present in the early Holocene of central Alaska, where it was the main hunted animal along with bison, and survived in Yukon until around 1400 BP (550 AD).

[92] There they are now considered an invasive species, encroaching on Argentinian ecosystems where they compete for food with the indigenous Chilean huemul and other herbivores.

[93] This negative impact on native animal species has led the IUCN to identify the elk as one of the world's 100 worst invaders.

[137] A male elk can produce 10 to 11 kilograms (22 to 24 lb) of antler velvet annually and on ranches in the United States, Canada and New Zealand, it is collected and sold to markets in East Asia, where it is used in medicine.

[139][140] Since 1967, the Boy Scouts of America have assisted employees at the National Elk Refuge in Wyoming by collecting the antlers which are shed each winter.