Classification of Living Organisms

The world of living organisms is extremely diverse. Biologists call these diverse forms 'species'. It is estimated that over fifteen lakh (1.5 million) species of living animals and plants are known, and more are yet to be discovered. On the other hand, millions of species have become extinct or have disappeared from the surface of the earth.

Individual of each species may be male or female, young or old and vary in shape, size, colour etc. The diversity of both extant and extinct animals and plants is so vast and confusing that it would be almost impossible for you to make any sense out of it unless it is arranged in some order. Arranging animals and plants into groups in an orderly manner on the basis of their similarity and relationships is called classification. This branch of science is known as taxonomy. Ernst Mayr, define, "taxonomy as the theory and practice of classification".