→ The method of arranging organisms into groups or sets on the basis of similarities anddifferences is called classification.

→ It makes the study of wide variety of organisms easy and in systematic manner.
→ It helps to understand how the different organisms have evolved with
→ It helps to understand the inter-relationships among different groups of organisms.
→ It forms a base for the study of other biological sciences, like biogeography.

Basis of Classification

→ There are certain features or properties used for the classification of living organisms which areknown as characteristics.
→ Organisms with same characteristics are placed in same groups.

Classification System

• Two kingdom classification:
Carolus Linnaeus in 1758 classified the living organisms into twogroups as plants and animals.
• Five kingdom classification:
H. Whittaker in 1959 further classified the organisms into fivekingdoms as Kingdom Monera, Kingdom Protista, Kingdom Fungi, Kingdom Plantae and Kingdom Animalia.

→ Carl Woese in 1977 further divided Kingdom Monera into archaebacteria (or Archae) andEubacteria (or Bacteria).