In order to improve analysis of the structuring of rural areas in mainland France, a new spatial nomenclature, a zonal classification in terms of «living basins», has been established. The living basin of a market town or small city is the smallest area which gives its inhabitants access to employment and everyday facilities. Having designated the 1,745 living basins linked to market towns and small cities, 171 territories emerge and are by analogy named «major agglomeration living basins». Living basins are territories structured around their centres which themselves contribute to the hierarchical structuring of the country and constitute a town and country planning tool.