Biodiversity is the degree of variation of life. The enormous variety of living organism found on Earth is called diversity or biodiversity. They show variety of shape, size and colour etc. The variation may be genetic variation, species variation or ecosystem variation within a biome.
Biodiversity varies greatly across the globe as well as within the region. Among other factors, the diversity of all living things (biota) depends on temperature, altitude, soils, geography and the presence of other species. The study of the spatial distribution of organisms, species, and ecosystems is the science of biogeography. These organisms are the result of evolution on the earth. Life originated about 3.5 billion years ago on the earth.
The range of global diversity of species known and described is around 1.7 – 1.8 million of which nearly a million species of animals and half a million of plant species are identified and described. Of these, 7, 50,000 are insects, 4,400 are fishes, 40,000 are invertebrates, 3, 50,000 are plants and 3, 60,000 are microorganisms.
Millions of plants and animals have been identified and described. But large numbers are still unknown. There are so many organisms with so many different characters which is impossible to remember so they are grouped into units like cattle, cows frogs and snakes etc. they differ in many features like occurrence, habit, structure and function. The scientists started to develop an overall system of classification of organisms about 300 years ago. The branch called as taxonomy or systematics.