Resources obtained from nature, i.e. from the earth are called natural resources. These resources occur naturally, and humans cannot make them. The raw materials used in artificial or man-made resources are natural resources.
Classification of natural resources can be done in several ways based on their origin, level of development and uses, stock or deposits, and their distribution.
On the basis of their origin, natural resources can be classified into living or biotic and non-living or abiotic resources.
If natural resources come from living things or organic materials, they are termed as living or biotic resources. Biotic resources include plants, animals and fossil fuels. Fossil fuels such as coal, oil and natural gas are classified as biotic resources as they are formed from the decay of organic matter over millions of years.
On the other hand, if the resources are derived from nonliving or inorganic materials, they are termed as abiotic resources. For instance, air, sunlight, and water are abiotic natural resources. Minerals are also considered abiotic.
On the basis of deposit or stock, natural resources can be classified as renewable and non-renewable.
Resources that can be used without any risk of its ending up are called renewable resources. They exist in unlimited quantity. Sun, water, wind, biomass, tides, geothermal energy, etc. are renewable resources. These are infinite sources of energy.
Those natural resources, on the other hand, that cannot be replenished after their depletion is called non-renewable resources. Most fossil fuels, such as coal, petroleum and natural gas are considered nonrenewable resources. Nonrenewable resources take billions of years for their formation, hence, their cautious and economic use is the only option left for mankind.
On the basis of development of resources, natural resources can be classified as actual and potential resources.
An actual resource is one which is used in current times. We know their approximate quantity, for example: coal deposit.
A potential resource is one whose utility is not known at present or is not used despite having the same. Instead, it may be useful at some time in future. In other words, such resources have the potential to have utility, although it does not have any today. For example, uranium deposit in Ladakh in India.