Bacterial taxonomy is the taxonomy, i.e. the rank-based classification, of bacteria. In the scientific classification established by Carl Linnaeus, each species has to be assigned to a genus (binary nomenclature), which in turn is a lower level of a hierarchy of ranks (family, suborder, order, subclass, class, division/phyla, kingdom and domain).In the currently accepted classification of life, there are three domains (Eukaryotes, Bacteria and Archaea), which, in terms of taxonomy, despite following the same principles have several different conventions between them and between their subdivisions as they are studied by different disciplines (botany, zoology, mycology and microbiology). For example, in zoology there are type specimens, whereas in microbiology there are type strains.