Taxonomy

- The science, laws, or principles of classification; systematics.

The taxonomic organization of species is hierarchical. Each species belongs to a genus, each genus belongs to a family, and so on through order, class, phylum, and kingdom. Associations within the hierarchy reflect evolutionary relationships, which are deduced typically from morphological and physiological similarities between species. So, for example, species in the same genus are more closely related and more alike than species that are in different genera within the same family.

Carolus Linnaeus, an 18th-century Swedish botanist, devised the system of binomial nomenclature used for naming species. In this system, each species is given a two-part Latin name, formed by appending a specific epithet to the genus name. By convention, the genus name is capitalized, and both the genus name and specific epithet are italicized, for Canis familiaris or simply C. familiaris.

Modern taxonomy recognizes five kingdoms, into which the estimated five million species of the world are divided. This table presents a familiar organism from each kingdom and the names of the taxonomic groups to which it belongs.

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