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
kingdom.jpg
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.
 
Figure_20_01_04ab.jpg
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.
 
PPT (5).png
Reference:
https://upload.wikimedia.org/wikipedia/commons/e/e5/SystemeOrganisationVivantCinqRegnesWhittaker1969.svg
https://upload.wikimedia.org/wikipedia/commons/0/06/Figure_20_01_04ab.jpg