At once the container of everyday life (i.e. where we live) and an active agent in it (a social-acting force). An incredibly wide-reaching term, with complex and even contradictory points of reference, it can refer to either the physical environment (built and natural) on its own or the physical environment as it is inhabited by defined groups of people, or both. Similarly, it can range in scale from the personal to the planetary. It is conceived differently by several different disciplines, each one emphasizing one or more of its facets---e.g. architecture, Cultural Studies, geography, history, sociology, planning, and urbanism---thus lending itself to an interdisciplinary approach. French Marxism sociologist Lefebvre, Henri is undoubtedly the most influential theorist of space in the twentieth century. His distinction between perceived space, conceived space, and lived space---i.e. space as we see it (but also touch it, feel it, and so on), space as we design and build it, and space as something we relate to in an emotional and affective way---captures the principal ways in which space has been thought about in the past century. Visual artists have tended to foreground perceived space, architects and urbanists have tended to focus on conceived space, with cultural studies, geography, and sociology claiming lived space as their own. But as Lefebvre insists, these three types of space can only be separated in the abstract and the real task of spatial thinking is to try to think of the three facets of space together. American geographer Soja, Edward refers to this process as trialectics and his work offers several interesting examples of how this can be made to work. The other major theorists of space in the twentieth century who have had a major influence on the field are: Bachelard, Gaston, Blanchot, Maurice, Merleau-Ponty, Maurice, Certeau, Michel de and AugĂ©, Marc. Michel de Certeau opposed space to place, defining the latter as what space becomes through the investment of power. By implication, space is the preserve of the powerless according to Certeau; those who dwell in space rather than place are forced to use tactics against strategy. Drawing on Certeauâs work, Marc AugĂ© created the concept of the non-place, which he also opposed to place: the non-place is a place invested by power that does not confer any of the benefits of place (such as belonging or locatedness)---his examples include subway systems, airports, and so on. In his highly influential synopsis of postmodernism, Jameson, Fredric argues that in the post World War II era there has been a mutation in the spatial environment. Drawing on Lefebvre, he foregrounds the fact that since 1945 there has been a massive demographic shift away from the country to the city, with the result that by the end of the century for the first time in human history more people live in cities than the country. But he also observes that in the West at least there has been a move towards creating structures that are self-contained, that seem to want to stand apart from the rest of the city, as though they were mini-worlds. His case in point, the Bonaventure Hotel in downtown Los Angeles, has become since his discussion of it a key topos of postmodernity. Further Reading: M. Doel Poststructuralist Geographies (1999). D. Gregory Geographical Imaginations (1994). N. Thrift Spatial Formations (1996).