Classification of living things

Biologists believe that there may be over two million (2,000,000) different kinds of organisms. Already over 1.5 million (1,500,000) different kinds have been identified and new ones are still being discovered. One biologist estimates that for each kind of organism now alive, another 400 kinds once lived but have since become extinct. Therefore, as many as one billion (1,000,000,000) different kinds of living things may have existed on the earth at one time or another.

How can we keep track of such a bewildering number of organisms? How can we even name the organisms now alive when no known language has two million words in it? Biologists have answers to these questions.

What is classification?

Whenever we work with a large number and variety of things, we usually sort them into groups. Each group contains those things that are similar to one another. We may then separate each of those groups into smaller groups that are even more alike.
The grouping of similar things for a specific purpose is called classification. Although it may be instinctive for human to classify things, there are also practical reasons for doing this. For example, a supermarket manager classifies the foods in his/her store by storing all the cereals together, all the meats together, all the cookies together, and so on. Stamp collectors classify their stamps. They place all the Canadian stamps in one page and all the American stamps in another. The words in a dictionary are classified by alphabetical listings. Clearly, we classify things to make it easier to keep track of what we have, and to find particular items.