The red deer (Cervus elaphus) is one of the largest deer species. The red deer inhabits most of Europe, the Caucasus Mountains region, Asia Minor, parts of western Asia, and central Asia. It also inhabits the Atlas Mountains region between Morocco and Tunisia in northwestern Africa, being the only species of deer to inhabit Africa. Red deer have been introduced to other areas including Australia, New Zealand and Argentina. In many parts of the world the meat (venison) from red deer is used as a food source.

Red deer are ruminants, characterized by an even number of toes, and a four-chambered stomach. Genetic evidence indicates that the red deer (Cervus elaphus) as traditionally defined is a species group rather than a single species, although it remains disputed exactly how many species the group includes (see Taxonomy). It is commonly accepted that the slightly larger wapiti (elk in American English), native to North America and eastern parts of Asia represents a distinct species besides red deer. The ancestor of all red deer, including wapiti, probably originated in Central Asia and probably resembled sika deer. I

Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths discernible by the human eye, in the wavelength range of roughly 630–740 nm. Longer wavelengths just past this range are called infrared (below red) and cannot be seen by the naked eye although they can be sensed as heat. In some cultures, certain shades of red are used to symbolize anger or aggression.

It is the color of blood when it is exposed to sunlight. In western countries, it is most commonly referred to as a color of evil, love, and sometimes, though rarely, happiness.

The word red comes from the Old English rēad. The word can be further traced to the Proto-Germanic rauthaz and the Proto-Indo European root reudh-. In Sanskrit, the word rudhira means red or blood. In the English language, the word red is associated with the color of blood, certain flowers (e.g., roses), and ripe fruits (e.g., apples, cherries). Fire is also strongly connected, as is the sun and the sky at sunset. Healthy, light-skinned people are sometimes said to have a "ruddy" complexion (as opposed to appearing pale). After the rise of socialism in the mid-19th century, red was used to symbolize and describe revolutionary movements.

Deer (singular and plural) are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, mule deer such as black-tailed deer, elk, moose, red deer, reindeer (caribou), fallow deer, roe deer and chital. Male deer of all species (except the Chinese water deer) and also female reindeer grow and shed new antlers each year. In this they differ from permanently horned animals such as antelope; these are in the same order as deer and may bear a superficial resemblance. The musk deer of Asia and water chevrotain (or mouse deer) of tropical African and Asian forests are not usually regarded as true deer and form their own families, Moschidae and Tragulidae, respectively.

The word "deer" was originally broad in meaning, but became more specific over time. In Middle English der (Old English dēor) meant a wild animal of any kind. This was as opposed to cattle, which then meant any sort of domestic livestock that was easy to collect and remove from the land, from the idea of personal-property ownership (rather than real estate property) and related to modern chattel (property) and capital. Cognates of Old English dēor in other dead Germanic languages have the general sense of "animal", such as Old High German tior, Old Norse djur or dȳr, Gothic dius, Old Saxon dier, and Old Frisian diar.