The three-domain system increase on a level of classification, the domains, over the kingdom currently in the earlier used five or six kingdom systems. The domains were added to the classification system of organisms, because a scientists find two prokayotic groups that were more different than previously thought. This classification system identified as the fundamental separate between the two prokaryotic groups, insofar as archaea become noticeable to be more closely connected to eukaryote than they are to other prokaryotic bacteria. The present system have the three domains kingdoms listed separate cellular life forms into:Domain Archaea, Domain Bacteria, and Domain Eukaryote.
