The term "region" is used in a wide range of contexts. It denotes an area that forms a unit owing to special characteristics. A region is always a middle-sized spatial unit, that is to say part of a larger unit and at the same time the sum of a group of smaller units. Since the beginning of the 1990s, “region” has become a vogue word, and even in the field of spatial planning a number of institutions have come to use it with reference to themselves, e.g., counties, regional associations, administrative districts, the states of the federation at the EU level, and innumerable informal regional cooperation projects. German regional planning is understood as a level of planning situated between the state and municipal levels. The area covered by a regional plan, the planning region, is thus, as defined above, both part of a state and a sum of counties and municipalities. Planning regions are constituted in keeping with spatial planning requirements.
Theoretically they should correspond to the catchment area of a high-order centre (as special characteristic), but in practice they are the territories of the counties affected or of an administrative district (Regierungsbezirk). For reporting purposes, federal spatial planning defines so-called spatial planning regions, which, however, often coincide with those for regional planning. Communities linked by strong commuter traffic form a common labour-market region.