An Ecosystem can be visualized as a functional unit of nature, where living organisms interact among themselves and also with the physical and chemical factors that make up its non-living and physical environment. The term ecosystem was first used by A. G. Tensley in 1935. On the basis of origin, ecosystems can be Natural (e.g. forest, desert, pond, lake etc) or Artificial ecosystems (e.g. croplands, townships etc).