The natural environment or natural world encompasses all living and non-living things occurring naturally, meaning in this case not artificial. The term is most often applied to Earth or some parts of Earth. This environment encompasses the interaction of all living species, climate, weather and natural resources that affect human survival and economic activity.
The concept of the natural environment can be distinguished as components:Complete ecological units that function as natural systems without massive civilized human intervention, including all vegetation, microorganisms, soil, rocks, the atmosphere, and natural phenomena that occur within their boundaries and their nature.
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 civilized human actions.
Land management has preserved the natural characteristics of Hopetoun Falls, Australia while allowing ample access for visitors.
An image of the Sahara Desert from satellite. It is the world's largest hot desert and third-largest desert after the polar deserts.
A volcanic fissure and lava channel
Coral reefs have significant marine biodiversity.
Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from matter that does not. It is defined descriptively by the capacity for homeostasis, organisation, metabolism, growth, adaptation, response to stimuli, and reproduction. All life over time eventually reaches a state of death and none is immortal. Many philosophical definitions of living systems have been proposed, such as self-organizing systems. Viruses in particular make definition difficult as they replicate only in host cells. Life exists all over the Earth in air, water, and soil, with many ecosystems forming the biosphere. Some of these are harsh environments occupied only by extremophiles.
Life
Animal corpses, like this African buffalo, are recycled by the ecosystem, providing energy and nutrients for living organisms.
Adenoviruses as seen under an electron microscope
Cyanobacteria dramatically changed the composition of life forms on Earth by leading to the near-extinction of oxygen-intolerant organisms.