Urban areas, in particular cities, are significant consumers of materials and energy, either directly on their land areas or indirectly through the materials, goods and services they import or export; there are upstream and downstream consequences of the removal of resources and the discharge of waste materials (to the atmosphere, water and soils), with multiple impacts on the biosphere. The processes involved need to be better characterised to reduce these environmental pressures. This is a sustainable development issue and it is a major goal of a field ecology which has been described as urban, industrial or sometimes territorial. This paper reviews the specific origins and findings of studies on urban metabolism. It describes the analysis tools used, including material and substance flows, energy balances, ecological, water and, more generally, environmental footprints. Finally, recent findings and areas for future research in the dematerialisation of urban societies are summarised.