Ecology is the science which studies the inter-relationships between biotic and abiotic components of a natural ecosystem on one hand and among biotic components on the other. Thus ecology is the study of interrelationships and various processes between all organisms and their environment as well as among the organisms themselves.

Ernst Haeckel coined the term ‘Oekology’ (Greek: oikos – house or dwelling as habitat, logos – study of). The concept of ecology evolved from Darwin’s concept of evolution of species through natural selection involving interaction between biological species and habitat.
Ecology is studied into two branches. First, autecology is the study of ecological relationship of single species in a given ecosystem. Second, synecology is the study of group of species living together as communities in relation to their habitats of a given ecosystem. It can be mentioned here that a group of individual organisms of the same species in a given area is called a population. While a group of population of different species in a given area is called a community. Based on this we have population ecology and community ecology.