The natural environment, commonly referred to simply as the environment, is all living and non-living things that occur naturally on Earth or some part of it (e.g. the natural environment in a country). This includes complete ecological units that function as natural systems without massive human intervention, including all vegetation, animals, microorganisms, rocks, atmosphere and natural phenomena that occur within their boundaries. And it includes universal natural resources and physical phenomena that lack clear-cut boundaries, such as air, water, and climate, as well as energy, radiation, electric charge, and magnetism, not originating from human activity.