Natural resources are naturally occurring substances that are considered valuable in their relatively unmodified (natural) form. A commodity is generally considered a natural resource when the primary activities associated with it are extraction and purification, as opposed to creation. Thus, mining, petroleum extraction, fishing, and forestry are generally considered natural-resource industries, while agriculture is not. The term was introduced to a broad audience by E.F. Schumacher in his 1970s book Small Is Beautiful.

Natural resources are often classified into renewable and non-renewable resources. Renewable resources are generally living resources (fish, coffee, and forests, for example), which can restock (renew) themselves at approximately the rate at which they are extracted, if they are not overharvested. Non-living renewable natural resources include soil, as well as water, wind, tides and solar radiation — compare with renewable energy.

Mineral resources are generally non-renewable and, once a site's non-renewable resource is exhausted, it is considered to be useless for future extraction, barring technological improvements that allow economic extraction from the tailings. Technological improvements may also allow future extraction of metals at lower concentrations than at previous times, which converts low-grade resources into ore, and may re-open or expand mines.

Both extraction of the basic resource and refining it into a purer, directly usable form, (e.g., metals, refined oils) are generally considered natural-resource activities, even though the latter may not necessarily occur near the former.

Natural resources are natural capital converted to commodity inputs to infrastructural capital processes. They include soil, timber, oil, minerals, and other goods taken more or less as they are from the Earth.

A nation's natural resources often determine its wealth and status in the world economic system, by determining its political nfluence. Developed nations are those which are less dependent on natural resources for wealth, due to their greater reliance on infrastructural capital for production. However, some see a resource curse whereby easily obtainable natural resources could actually the prospects of a national economy by fostering political corruption.

In recent years, the depletion of natural capital and attempts to move to sustainable development have been a major focus of development agencies. This is of particular concern in rainforest regions, which hold most of the Earth's natural biodiversity - irreplaceable genetic natural capital. Conservation of natural resources is the major focus of Natural Capitalism, environmentalism, the ecology movement, and Green Parties. Some view this depletion as a major source of social unrest and conflicts in developing nations.