A couronne périurbaine, a statistical area devised by the French INSEE

INSEE

INSEE is the French National Institute for Statistics and Economic Studies. It collects and publishes information on the French economy and society, carrying out the periodic national census. Located in Paris, it is the French branch of Eurostat, European Statistical System...

 demographic statistics institution, describes a commuter belt area around an area of dense habitation (or unité urbaine

Unité urbaine

In France an unité urbaine is a statistical area defined by INSEE, the French national statistics office, for the measurement of contiguously built-up areas...

to use the same institution's terminology).

Based on France's commune system (interlocking administrative subdivisions often comparable to civil parishes

Civil parish

In England, a civil parish is a territorial designation and, where they are found, the lowest tier of local government below districts and counties...

, towns

Town

A town is a human settlement larger than a village but smaller than a city. The size a settlement must be in order to be called a "town" varies considerably in different parts of the world, so that, for example, many American "small towns" seem to British people to be no more than villages, while...

 or cities

City

A city is a relatively large and permanent settlement. Although there is no agreement on how a city is distinguished from a town within general English language meanings, many cities have a particular administrative, legal, or historical status based on local law.For example, in the U.S...

), a commune is considered part of a couronne périurbaine when

1. it is not densely-constructed enough or is too isolated to be part of any unité urbaine
   Unité urbaine
   In France an unité urbaine is a statistical area defined by INSEE, the French national statistics office, for the measurement of contiguously built-up areas...
   
   (or "pôle urbain
   Pôle urbain
   In France, a pôle urbain is a statistical area defined by INSEE for the measurement of contiguously built-up areas...
   
   " if it is the core of the agglomeration), and
2. at least 40% of its population commutes to workplaces in a unité urbaine
   Unité urbaine
   In France an unité urbaine is a statistical area defined by INSEE, the French national statistics office, for the measurement of contiguously built-up areas...
   
   or pôle urbain
   Pôle urbain
   In France, a pôle urbain is a statistical area defined by INSEE for the measurement of contiguously built-up areas...
   
   , or to another commune connected to a unité urbaine
   Unité urbaine
   In France an unité urbaine is a statistical area defined by INSEE, the French national statistics office, for the measurement of contiguously built-up areas...
   
   through the same criteria.