The world about us can be looked at in a variety of ways. One way is to see the world as made up from many interacting systems: weather, societal, economic, ecological, floral, faunal, tectonic plate, oceanic, and so on. This is very much a connected view of the world: nothing is isolated and totally independent; everything is part of something bigger, and everything comprises many interacting parts — subsystems.

Derek Hitchins (2013) at "Systems World" at hitchins.net