A RESOURCE IS any item or substance that is in scarce supply and has some value. Resources are normally considered to be physical items, such as oil and natural gas. However, it is also possible to consider humans resources, since they are finite in number and are perishable under current technological conditions. Resources, when used in the context of computer or virtual environments, meanwhile, are inherently intangible in nature, although the hardware that produces them is not.

It is customary, when considering resources, to distinguish between those that are renewable and those that are nonrenewable. Resources such as oil are consumed in use and are, therefore, nonrenewable. However, in a number of other cases, it is possible to recreate or recycle some resources either in the ...