The central-place system goes back to the work of Walter Christaller (1933). Since the 1960s, it has had a decisive influence on the spatial planning strategies for developing settlement structure in the Federal Republic of Germany. The central-place classificatory system is an important tool in state and regional planning, and is laid down in spatial structure plans. In addition to supplying the needs of its own population, a central place performs service and development functions for the population of its catchment area. The central place system constitutes a hierarchy of basic, lower-order or small centres, middle-order centres, and high-order centres as determined at the different levels of state spatial planning. Some states insert intermediate categories in the hierarchy. Depending on their assignment to a central place, catchment areas are defined as local, intermediate or extended areas.
The lowest level in the hierarchy is occupied by basic centres (low-order centres, small centres) with a local catchment area. They are designated in regional plans, and their functions include supplying the basic daily needs of the population and providing a minimum of public and private infrastructure (general secondary school, doctor, chemist, tradesmen, etc.).
Middle-order centres are central places that meet more demanding, medium-term needs of the population in the intermediate catchment area (secondary schools leading to university entrance, hospitals, a variety of shopping amenities, etc.), and are designated by state spatial planning. They are also labour-market centres for their catchment area.
High-order centres are also designated by state spatial planning and meet demanding, specialisedrequirements of the population in the extended catchment area (technical colleges / universities, specialised clinics, large department stores, etc.). High-order centres also have a greater supply of highly qualified and skilled labour.