Taxonomy: Taxonomy is the discipline that deals with classification of biological organisms in specific groups based on their physical and biological characteristics. The system by which a biological organism is classified and given a name is called binomial nomenclature. Carl Linnaeus introduced the rank-based system of nomenclature into biology. In his system of classification, the highest rank was given the name kingdom.
Hierarchy: The hierarchy is given as: A) Kingdom B) Phylum (Animals) or Division (Plants) C) Class D) Order E) Family F) Genus G)Species
Six kingdom system in the United States: In the United States a six kingdom system consisting of Animalia, Plantae,Fungi, Protista, Archaea, and Bacteria is followed. In Britain, Australia and Latin America, the five kingdom system including Animalia, Plantae, Fungi, Protoctista, and Prokaryota or Monera is followed.
Recent classification systems: Recent classification systems have excluded the term kingdom, noting that the traditional kingdoms are not monophyletic, that is, they do not consist of all the descendants of a common ancestor.
Other common changes in the modern system of classification: Other common changes in the modern system of classification include: A) Subkingdom and Infrakingdom are the two ranks immediately below kingdom. B) Superkingdom may be considered as an equivalent of domain or empire or as an independent rank between kingdom and domain. C) In some classification systems the additional rank called ‘branch’ is included between subkingdom and infrakingdom.