An (urban) agglomeration (largely synonymous with conurbation, metropolitan area) is a concentration of settlements consisting of interlinked and interdependent communities distinguished from surrounding areas by greater settlement density and a higher proportion of built development. As a rule, agglomerations form around one or more core cities surrounded by heavily built-up inner rings of suburbs and geographically more extensive, partly rural catchment areas.
The core or central city with the suburban belt is referred to as an urban region. Major cities with international status and their extensive catchment areas are termed metropolitan regions. With a high concentration of housing and workplaces, urban agglomerations drive economic development and are loci of cultural life. They are accordingly important for the country as a whole. In terms of spatial category, agglomerations or conurbations are the type of area with the highest use density, being the opposite pole to sparsely population rural areas. Communication axes between agglomerations, which partly traverse rural areas, are termed corridors.