An ecosystem consists of a community of organisms together with their physical environment.
Ecosystems can be of different sizes and can be marine, aquatic, or terrestrial. Broad categories of terrestrial ecosystems are called biomes.
In an ecosystem, both matter and energy are conserved. Energy flows through the system—usually from light to heat—while matter is recycled. Example - a community consists of all the populations of all the species that live together in a particular area.
