Taxonomy is the science and methodology of classifying organisms based on physical and other similarities. Taxonomists classify all organisms into a hierarchy, and give them standardized Latin or Latinized names.

The Linnaean taxonomy is a system of classification widely used in the biological sciences. It was first developed by Carolus Linnaeus in the 18th century during the great expansion of natural history knowledge. Linnaean taxonomy classifies living things into a hierarchy, starting with domains or kingdoms. Kingdoms are divided into phyla (singular: phylum)—for animals; the term divisions is used for plants. Phyla are divided into classes, and they, in turn, into orders, families, genera (singular: genus), and species (singular: species). Groups of organisms at any of these ranks are called taxa (singular: taxon), or phyla, or taxonomic groups.

A summary of this scheme, from most general to most specific, would be:

Kingdom - The highest taxonomic classification into which organisms are grouped, based on fundamental similarities and common ancestry. One widely accepted taxonomic system designates five such classifications: animals, plants, fungi, prokaryotes, and protoctists.

Phylum - A primary division of a kingdom, as of the animal kingdom, ranking next above a class in size.

Class - A unit of scientific classification that comes after order but before genus/genera in terms of biological relationships

Order - A taxonomic category of organisms ranking above a family and below a class.

Family - A taxonomic category of related organisms ranking below an order and above a genus. A family usually consists of several genera.

Genus - A taxonomic category ranking below a family and above a species and generally consisting of a group of species exhibiting similar characteristics. In taxonomic nomenclature the genus name is used, either alone or followed by a Latin adjective or epithet, to form the name of a species.

Species - A fundamental category of taxonomic classification, ranking below a genus or subgenus and consisting of related organisms capable of interbreeding.