In biological taxonomy, a domain (also superregnum, superkingdom, or empire) is the highest taxonomic rank of organisms, higher than a kingdom. According to the three-domain system of Carl Woese, introduced in 1990, the Tree of Life consists of three domains: Archaea, Bacteria and Eukarya. The arrangement of taxa reflects the fundamental differences in the genomes. There are some alternative classifications of life:
None of the three systems currently include non-cellular life.
Domain (or its synonyms) is the most inclusive of these biological groupings. The arrangement of taxa reflects the fundamental evolutionary differences in the genomes. There are several modern alternative domain classifications of life. Among them are:
and the most recent,