Nature and human beings are closely related. In fact, the very existence of human life depends on the nature or environment. Environmentmeans all the living and non-living things around us such as Animals, Plants, Forests, Farms, Continents, Oceans, Clouds, Ice caps, Rivers, Structures, Urban centres, Living places, etc. The environment may be defined as an outer physical and biological system in which man and other organisms live with many interacting components. Or in another words

“The sum total of all surroundings of a living organism, including physical, biological and chemical factors, which provide conditions for development and growth of that living organism.”

There is a close interaction among various components which seem to produce some kind of equilibrium in the scheme of nature, what is usually termed as ecological balance. We depend completely on the environment for survival. Natural systems have been degraded by pollution, soil erosion, species extinction etc. by this environmental changes it threaten our long term well-being and survival.


It is the systematic study of how the natural world works, how the environment affects humans and vice versa or the interrelationship or interaction between living beings and environment. Or it can be taken as an integrated approach to addressing environmental problems. We need to understand our interaction or relationship with the environment to creatively solve environmental problems. That’s why environmental science has a prime importance. Identifying a problem is the first step in solving it and environmental science does that.


Ecology is the science that deals with the various principles, which govern the relationship and interdependence between the organismsand their environment. The term ecology is derived from two Greek words, Oikos and Logos. Oikos means home or habitation or a place to live in. Logos means study or discourse. Hence, literally speaking, ecology is the study of organisms in their own habitat or the ecology has been defined as the study of structure and functions of nature. Ecology has been broadly divided in to autecology and synecology.Autecology deals with the relationship of one species of organism. An Autecologist studies the life history, population, dynamics, behaviour, home range of a single species. Synecology deals with the ecological studies of communities or an entire ecosystem. It describes the overall energy and material flow through the system.

The main objectives of ecology is to study the relationships between living organism and environment, analyse the interdependence between organisms and environmental components, evolve scientific approaches for controlling and regulating the welfare of living organisms, study the conservation and management of natural resources and environmental pollution. It is the main focus of applied ecology, observe the biological productivity of physical environment or nature and how the products may best serve the mankind or improve the quality of man. It is the main aim of ecosystem ecology.