Taxon
A taxon is a named group of organisms recognized as a unit in biological classification, at any rank from species to kingdom.
Biological classification: The organization of organisms into named groups based on shared traits and evolutionary relationships. Taxa are the units that biological classification names and arranges.
Taxonomy: The practice and theory of discovering, describing, naming, and classifying organisms. Taxonomy establishes and revises the taxa recognized in classification.
Monophyletic group: A group containing a common ancestor and all of its descendants. Many modern classifications aim to make taxa monophyletic.
International Code of Zoological Nomenclature: The rules governing the scientific names of animals. Its rules determine how animal taxon names are established and prioritized.
Taxonomic rank: A level in a classification hierarchy, such as species, genus, family, or order. A taxon can occupy any rank in the hierarchy.
Cladistics: A method of classification that groups organisms by shared derived characters and common ancestry. Cladistics favors taxa that represent complete branches of ancestry.
Paraphyletic group: A group containing a common ancestor and some, but not all, of its descendants. Some traditional taxa exclude descendants and are therefore paraphyletic.
International Code of Nomenclature for algae, fungi, and plants: The rules governing scientific names of algae, fungi, and plants. Its provisions stabilize names across several major groups of taxa.
Species: A basic taxonomic rank whose boundaries are defined differently across species concepts and groups of organisms. Species is the lowest rank commonly used for naming taxa.
Type specimen: A preserved specimen designated as the name-bearing reference for a species or other taxon. A type specimen anchors a taxon's name to a physical reference.