The highest level of ecological organization encompasses all living organisms on Earth, together with their surrounding physical and chemical environment.

Ecosystem:

An ecosystem is a self-contained community of living organisms in conjunction with the non-living components of their environment (things like air, water and soil), interacting as a system.

Community:

A community represents a collection of different populations of species that inhabit a particular area and interact with one another.

Population:

A population consists of a group of organisms of the same species living in the same area.

Organism:

An organism is an individual living entity, capable of carrying out life processes such as metabolism, reproduction, growth and response to stimuli.