There are 3 domains that separate all life into the 6 kingdoms. The domains are Archaea, Bacteria, and Eukarya. Archaea and Bacteria are prokaryotes consisting of single-celled organisms, while Eukarya contains the eukaryotic kingdoms of Protista, Fungi, Plantae, and Animalia which can be single or multi-cellular. The kingdoms are further separated based on characteristics like cell structure, nutrition, nervous systems, and motility.