The genus is native to Africa and is common in South Africa's Cape Province and the mountains of tropical Africa, and neighbouring areas such as Madagascar, the Arabian peninsula and the islands off Africa.

The APG II system (2003) placed the genus in the family Asphodelaceae. In the past it has also been assigned to families Aloaceae and Liliaceae. Members of the closely allied genera Gasteria, Haworthia and Kniphofia which have a similar mode of growth, are also popularly known as aloes. Note that the plant sometimes called "American aloe" (Agave americana), belongs to Agavaceae, a different family.