Urbanism is the study of how inhabitants of urban areas, such as towns and cities, interact with the built environment. It is a direct component of disciplines such as urban planning, which is the profession focusing on the physical design and management of urban structures and urban sociology which is the academic field the study of urban life and culture. Many architects, planners, geographers, and sociologists investigate the way people live in densely populated urban areas. There is a wide variety of different theories and approaches to the study of urbanism. However, in some contexts internationally, urbanism is synonymous with urban planning, and urbanist refers to an urban planner. The term urbanism originated in the late nineteenth century with the Spanish engineer-architect Ildefons Cerda, whose intent was to create an autonomous activity focused on the spatial organization of the city. Urbanism's emergence in the early 20th century was associated with the rise of centralized manufacturing, mixed-use neighborhoods, social organizations and networks, and what has been described as "the convergence between political, social and economic citizenship". Urbanism can be understood as placemaking and the creation of place identity at a citywide level, however as early as 1938 Louis Wirth wrote that it is necessary to stop 'identify[ing] urbanism with the physical entity of the city', go 'beyond an arbitrary boundary line' and consider how 'technological developments in transportation and communication have enormously extended the urban mode of living beyond the confines of the city itself.' Concepts Network-based theories Gabriel Dupuy applied network theory to the field of urbanism and suggests that the single dominant characteristic of modern urbanism is its networked character, as opposed to segregated conceptions of space (i.e. zones, boundaries and edges). Stephen Graham and Simon Marvin argue that we are witnessing a post-urban environment where decentralized, loosely connected neighborhoods and zones of activity assume the former organizing role played by urban spaces. Their theory of splintering urbanism involves the "fragmentation of the social and material fabric of cities" into "cellular clusters of globally connected high-service enclaves and network ghettos" driven by electronic networks that segregate as much as they connect. Dominique Lorrain argues that the process of splintering urbanism began towards the end of the 20th century with the emergence of the gigacity, a new form of a networked city characterised by three-dimensional size, network density and the blurring of city boundaries. Manuel Castells suggested that within a