Theory:

Hierarchy of  classification
The living organisms were classified into broad categories known as kingdoms by Carolus Linnaeus in $$1758$$ firstly. He classified the organisms into two kingdoms known as Plantae and Animalia. Thus, his classification was known as two-kingdom classification. Later on, biologists such as Ernst Haeckel ($$1894$$), Robert Whittaker ($$1969$$) and Carl Woese ($$1977$$) played major roles in the classification.

Based on the cell structure, mode and source of nutrition and body organisation, Robert Whittaker classified living organisms into five kingdoms such as,
• Monera
• Protista
• Fungi
• Plantae
• Animalia
The tree of five kingdom classification
Carl Woese divided the kingdom monera into archaea or archaebacteria and eubacteria or bacteria.
In further classification, the sub-groups are named at various levels as following.

Hierarchy of classification of Canis lupus
The separation of the organisms into smaller and smaller groups of the basis of a hierarchy of characteristics finally ends at the basic unit of classification known as species.
All the organisms that are similar enough to breed belong to a species.

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