All living organisms are grouped into three large groups called domains. They are: Bacteria, Archae, and Eukarya. The domains Bacteria (eubacteria or “true” bacteria) and Archae (archaebacteria or “ancient” bacteria) consist of unicellular organisms with prokaryotic cells. The domain Eukarya consists of four kingdoms: Protista, Fungi, Plantae, and Animalia. Organisms in these groups have eukaryotic cells. Eukaryon means “true nucleus.”