In biology, a domain (also superregnum, superkingdom, or empire) is the top-level grouping of organisms in scientific classification, higher than a kingdom.

Today there are several competing domain classifications of life:

• The three-domain system of Carl Woese, introduced in 1990, with top-level groupings of Archaea, Eubacteria, and Eukaryota domains.
• The two-empire system, with top-level groupings of Prokaryota (or Monera) and Eukaryota empires.
• The five-kingdom system with top-level groupings of Protista, Monera, Fungi, Plantae, and Animalia.

Scientific classification

Domein (biologie) | Domini taxonòmic | Domæne (biologi) | Domäne (Taxonomie) | Domeen (bioloogia) | Dominio (biología) | Dominio (biologia) | Domein (biologie) | Domena (biologia) | Super reino | Домен (биология) | Domän (biologi) | 域 (生物)