Ecology (from Greek: oikos, "household"; and logos, "knowledge") is the scientific study of the distribution and abundance of life and the interactions between organisms and their natural environment. The environment of an organism includes physical properties, which can be described as the sum of local abiotic factors such as insulations (sunlight), climate, and geology, and biotic ecosystem, which includes other organisms that share its habitat.

The word "ecology" is often used more loosely in such terms as social ecology and deep ecology and in common parlance as a synonym for the natural environment or environmentalism. Likewise "ecologic" or "ecological" is often taken in the sense of environmentally friendly.

The term ecology or Ökologie was coined by the German biologist Ernst Haeckel in 1866, when he defined it as "the comprehensive science of the relationship of the organism to the environment.