There are three types of resources in the world: renewable, non-renewable, and perpetual.  Perpetual resources are not affected by human use of them.  Examples are sunlight and wind.

Renewable resources are those that are replenished through biogeochemical and physical cycles.  By contrast, non-renewable resources do not replenish themselves, or, as in the case of fossil fuels, do so only at a very slow rate.

A Forest.  Photo Credit: ClickART Image Pak.

Renewable resources are seldom perfectly renewable.  If their levels are heavily decreased, they may not be able to completely replenish themselves.  For example, if a species is nearly eradicated, it may not be able to avoid extinction.

Renewable resources can also be lost through pollution.  Though water renews itself, if it is polluted, it is no longer useful for human use.  Urban sprawl, cultivation, irrigation, grazing, deforestation, fishing, hunting, and habitat destruction can all be causes of the destruction of an otherwise renewable resource.

There are both organic and inorganic types of renewable resources.  Examples of renewable organic substances include plant and animal species.  Inorganic examples include water and certain gases like oxygen.

During different periods of time, different things are thought of as resources.  As the usefulness of certain resources like wind have varied, their classification has changed too.

There have been numerous efforts to prevent the mistakes that lead to the depletion of renewable resources.  Despite this, destruction of renewable resources often proves to be profitable, and happens as a result.