a concept in taxonomy, used to designate a coordinate group of objects—a taxon. In the classification of a specific sphere of reality, the system of taxonomic categories constructed must give a complete description of the reality from the standpoint of the hierarchical structure; such are the taxonomic categories, for example, that describe animal or plant systematics. Thus, taxonomic categories directly characterize not the concrete objects of classification, but only the method of the classification’s construction and the logical principles that resolve problems of typology.