Natural resources may be biotic, or deriving from living organisms or organic materials, or abiotic, which come from inorganic materials. A natural resource is a raw material, or a non-human made material provided by the Earth or environment, which humans can use in a variety of ways.
Biotic natural resources include animals, plants and also fossil fuels, such as coal, oil and natural gas. Fossil fuels are so-called because they are formed from the decaying process of what were once living organisms millions of years ago.
Abiotic natural resources include air, sunlight, water and minerals, such as gold, diamonds and other metals.
Natural resources can be used or modified in a myriad of ways by human beings and are often given monetary value because of their end use. Petroleum products, for example, are exploited and sold in the marketplace while sunshine, which fuels solar power and also takes a vital role in the photosynthesis of plants and therefore commercial crops, does not have a monetary value.
The perceived value of natural resources depends on the human context and most often a simplistic view that looks at immediate monetary value only. Undeveloped land may not be seen as having a monetary value but natural systems do provide materials essential to human life, such as oxygen production.