A non-renewable resource is one that either does not regenerate or does not regenerate quickly enough to serve some human purpose in a sustainable way.
The most common examples of non-renewable resources are fossil fuels, such as coal, oil and natural gas. Although these resources form naturally within the earth, they take billions of years to do so. Other non-renewable resources include metals, minerals and stone.
Resources considered renewable are those that are readily replenished such as solar, geothermal, wind and tidal energy. Energy derived from such sources is often called green power or clean electricity because it doesn’t deplete non-renewable resources or cause pollution.
Some resources, although they regenerate, do not do so very quickly and are in danger of depletion in many locations because of overuse. There is some disagreement over whether such resources as wood and potable water are, in a practical sense, renewable.
How Stuff Works explains renewable and non-renewable resources: