It is a common knowledge that no organism lives by itself alone. It must live in the same environment with other organisms either of its own kind or with those of other kinds. This means that an organism lives in a population occupying a particular habitat and thus interacts with other members of a population in different ways. This is also true that a particular habitat supports populations of different organisms which also interact both in spatial and food terms thereby forming a biotic community. Living as such, an organism may eat up other organisms or be eaten by others. At the same time, it also competes with others for the necessities of life such as space, food (sunlight in case of plants), protection, mate, etc.

However, it must be noted that an organism does not merely interact with other organisms what we call as biotic elements of its habitat but also with its physical environment what we call as a- biotic component where it continually makes adjustments to maximize its survival. In this sense, we can say that every organism is influenced by and influences the life and physical environment around it.

 The study of this  total relationship of an organism with both its living and non living environment is what was referred to as “ecology” by the German naturalist, Ernst Haeckel way back in 1869.

 The term “ecology” is derived from the Greek words: "oikos" meaning house or a place to live in and "logos” meaning a discourse on or study or knowledge. Ecology is also called bionomics (bio- (economics).

In simplest terms thus, ecology is all about the study of an organism in relation to its environment. While the environment of an organism includes both the biotic and abiotic factors. These environmental factors affect the morphology, physiology, growth, distribution, behaviour and survival of an organism.

In a nutshell, the question that how these aspects of life of an organism are influenced by the environment and how the organisms affect the environment from the subject matter of ecological studies.

Ecological studies give us the scientific foundations for our understanding of agriculture, forestry and fisheries. Besides this, ecology also gives us the basis for predicting, preventing and remedying pollution. Indeed then, ecology also helps us to understand the likely consequences of massive environmental intervention, as in the construction of dams or diversion of rivers and thus provides the rationale underpinning biological conservation. This is why the most pressing problems that beset mankind  today, such as need for increasing productivity, dwindling energy supplies ; population explosion; pollution of air, water, and soil ; protection of animal and plant species from extinction; deforestation land degradation ; floods, conservation of resources etc. are all directly or indirectly linked with ecology. Under such circumstances, there is a pressing need for associating ecologists in the country’s planning process so that the environmental impact of ecology could be assessed well in advance…Let's start with some basic concept of basic concepts of ecology.