CoachEvery species has a binomial name: the name of its genus (capitalised) followed by a specific epithet, both in italics — Homo sapiens, Quercus robur, Escherichia coli — often followed by the author and year of its description. The system, fixed by Linnaeus in 1753 (plants) and 1758 (animals), nests species in a hierarchy of ranks: genus, family, order, class, phylum (or division), kingdom, domain. A group at any rank is a taxon. Each name is tied to a type specimen, deposited in a museum or herbarium, which fixes what the name refers to; the oldest valid name has priority; and the rules are codified so that one organism has one name worldwide. The ranks are conventions — there is no property that all families share and no genus does; only the species is a natural unit.
