"Industrial Ecology" explores the idea that industrial activities should not be considered in isolation from the natural world but rather as a part of the natural system. In fact industrial systems should be viewed as industrial ecosystems that function within the natural ecological system or biosphere. The industrial system, in a similar way to the natural ecosystem, essentially consists of flows of materials, energy and information, and furthermore relies on resources and services provided by the biosphere. It is important to stress that the word 'industrial', in the context of "Industrial Ecology", refers to all human activities occurring within the modern technological society. Therefore, tourism, housing, medical services, transportation and agriculture are all part of the industrial system. And the word 'ecology', here, refers to the science of ecosystems.