There are four overseas regions : Guadeloupe, French Guiana, Martinique, and Réunion. The common name is ROM's or Regions de Outre-Mer.
The ROM's are also DOM's (Departements de Outre-Mer) with the same political structure.
The national government is represented by the Prefect, who is appointed by the national executive.
Each department is subdivided into arrondissements which have a sous prefect and sous prefecture. There are 12 overseas arrondissements.
Arrondissements are divided into Cantons. Cantons are a grouping of communes used as the base for regional elections. The Cantons date back to the French revolution. There are 153 overseas cantons.
A 19thC structure allowing co-operation between communes with a common interest. They are typically composed of communes sharing a river valley or other facilities.
Some are fairly informal, and communes contribute to the shared costs. However, others, are able to raise their own taxes through the tax professionelle of residents.
Those raising taxes are community of communes (normally rural), community of agglomeration (medium sized cities).
There are 15 such communities in overseas France. A commune can belong to more than one intercommunality.
There are 112 communes in overseas France. Some communes include (confusingly) several cantons.
French communes have a town hall, mayor and a group of councillors. Elections are held every 6 years.
Other overseas interests
France has other overseas interests. They are eligible to vote for the French national assembly and are represented in the Senate. They participate in presidential elections, but have varying degrees of independence. They are not part of EU.
(collectivités d'outre-mer, or COM's) :
Saint-Pierre and Miquelon
Wallis and Futuna
Sui generis collectivity
(collectivité sui generis): New Caledonia,
(territoire d'outre-mer, or TOM): the French Southern and Antarctic Lands, which have no permanent population :
Amsterdam Island and Saint Paul Island
Scattered Islands (îles Éparses), Bassas da India, Europa, Juan deNova, Glorioso, and Tromelin.