In biological classification, family (Latin: familia, plural familiae) is 1) a rank or 2) a taxon in that rank. Example: "Walnuts and Hickories belong to the Walnut family" is a brief way of saying: the Walnuts (genus Juglans) and the Hickories (genus Carya) belong to the Walnut family (family Juglandaceae). Next only to species and genus, the family is the most important rank in taxonomy. Exact details of formal nomenclature depend on the Nomenclature Code which applies, see scientific classification and: * Rank (botany) * Rank (zoology) * Virus classification