'Natural resources' are naturally occurring substances that are considered valuable in their relatively unmodified (natural) form. A natural resource's value rests in the amount of the material available and the demand for it. There are 2 types of natural resources: renewable and non-renewable. Natural Resources include soil, timber, oil, minerals, and other goods taken more or less from the Earth. 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. A nation's natural resources often determine its wealth in the world economic system. 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. This book gathers and presents important research in the field.