<P> Taxonomy (from Ancient Greek τάξις (taxis), meaning' arrangement', and - νομία (- nomia), meaning' method') is the science of defining and naming groups of biological organisms on the basis of shared characteristics . Organisms are grouped together into taxa (singular: taxon) and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a super group of higher rank, thus creating a taxonomic hierarchy . The principal ranks in modern use are kingdom, phylum, class, order, family, genus and species . The Swedish botanist Carl Linnaeus is regarded as the father of taxonomy, as he developed a system known as Linnaean taxonomy for categorization of organisms and binomial nomenclature for naming organisms . </P> <P> With the advent of such fields of study as phylogenetics, cladistics, and systematics, the Linnaean system has progressed to a system of modern biological classification based on the evolutionary relationships between organisms, both living and extinct . </P> <P> The exact definition of taxonomy varies from source to source, but the core of the discipline remains: the conception, naming, and classification of groups of organisms . As points of reference, recent definitions of taxonomy are presented below: </P> <Ol> <Li> Theory and practice of grouping individuals into species, arranging species into larger groups, and giving those groups names, thus producing a classification </Li> <Li> A field of science (and major component of systematics) that encompasses description, identification, nomenclature, and classification </Li> <Li> The science of classification, in biology the arrangement of organisms into a classification </Li> <Li> "The science of classification as applied to living organisms, including study of means of formation of species, etc ." </Li> <Li> "The analysis of an organism's characteristics for the purpose of classification" </Li> <Li> "(Systematics) studies phylogeny to provide a pattern that can be translated into the classification and names of the more inclusive field of taxonomy" (listed as a desirable but unusual definition) </Li> </Ol>

Where does domain go in the 7 levels of classification