A hart is a male red deer, synonymous with stag and used in contrast to the female hind; its use may now be considered mostly poetic or archaic. The word comes from Middle English hert, from Old English heorot; compare Frisian hart, Dutch hert, German Hirsch, and Swedish, Norwegian, and Danish hjort, all meaning "deer". Heorot is given as the name of Hrothgar's mead hall in the Old English epic Beowulf.

The red deer is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a doe or hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of western Asia. It also inhabits the Atlas Mountains of Northern Africa; being the only living species of deer to inhabit Africa. Red deer have been introduced to other areas, including Australia, New Zealand, the United States, Canada, Peru, Uruguay, Chile and Argentina. In many parts of the world, the meat (venison) from red deer is used as a food source.