When Carl Linnaeus introduced the rank-based system of nomenclature into biology in 1735, the highest rank was given the name "kingdom" and was followed by four other main or principal ranks: See more

Two kingdoms of life
The classification of living things into animals and plants is an ancient one. Aristotle (384–322 BC) classified animal species in his See more

While the concept of kingdoms continues to be used by some taxonomists, there has been a movement away from traditional kingdoms, as they are no longer seen as providing a cladistic classification, where there is emphasis in arranging organisms into See more

The International Committee on Taxonomy of Viruses uses the taxonomic rank "kingdom" in the classification of viruses (with the suffix -virae); but this is beneath the top level classifications of realm and subrealm.
There is ongoing … See more

• Biology portal
• Cladistics
• Phylogenetics
• Systematics See more

• Pelentier, B. (2007-2015). Empire Biota: a comprehensive taxonomy, . [Historical overview.]
• Peter H. Raven and Helena Curtis (1970), Biology of Plants, New York: Worth Publishers. [Early presentation of five-kingdom system.] See more

• A Brief History of the Kingdoms of Life at Earthling Nature
• The five kingdom concept Archived 2021-11-07 at the Wayback Machine
• Whittaker's classification See more