Corsica ( KOR-sik-, Upper Corsican: [korsia], Southern Corsican: [krsika], Italian: [krsika]; French: Corse [ks] (listen); Ligurian: Crsega) is an island in the Mediterranean Sea and one of the 18 regions of France. It is the fourth-largest island in the Mediterranean and lies southeast of the French mainland, west of the Italian Peninsula and immediately north of the Italian island of Sardinia, which is the land mass nearest to it. A single chain of mountains makes up two-thirds of the island. As of January 2022, it had a population of 349,465.The island is a territorial collectivity of France. The regional capital is Ajaccio. Although the region is divided into two administrative departments, Haute-Corse and Corse-du-Sud, their respective regional and departmental territorial collectivities were merged on 1 January 2018 to form the single territorial collectivity of Corsica. As such, Corsica enjoys a greater degree of autonomy than other French regional collectivities; for example, the Corsican Assembly is permitted to exercise limited executive powers. Corsica's second-largest town is Bastia, the prefecture of Haute-Corse.

Corsica was ruled by the Republic of Genoa from 1284 to 1755, when it seceded to become a self-proclaimed, Italian-speaking Republic. In 1768, Genoa officially ceded it to Louis XV of France as part of a pledge for the debts it had incurred by enlisting France's military help in suppressing the Corsican revolt, and as a result France went on to annex it in 1769. The future Emperor of the French, Napoleon Bonaparte, was a native Corsican, born that same year in Ajaccio: his ancestral home, Maison Bonaparte, is today a visitor attraction and museum. Because of Corsica's historical ties to Tuscany, the island has retained many Italian cultural elements and many Corsican surnames are rooted in the Italian peninsula. Corsican, the native tongue, is recognised as one of France's regional languages. Corsica is the smallest region of metropolitan France by population, and the third-smallest overall after Mayotte and French Guiana.

In the administrative divisions of France, the department (French: département, pronounced [depaʁtəmɑ̃]) is one of the three levels of government under the national level ("territorial collectivities"), between the administrative regions and the communes. Ninety-six departments are in metropolitan France, and five are overseas departments, which are also classified as overseas regions. Departments are further subdivided into 332 arrondissements, and these are divided into cantons. The last two levels of government have no autonomy; they are the basis of local organisation of police, fire departments and, sometimes, administration of elections.

Each department is administered by an elected body called a departmental council (conseil départemental [sing.], conseils départementaux [plur.]). From 1800 to April 2015, these were called general councils (conseil général [sing.] conseils généraux [plur.]). Each council has a president. Their main areas of responsibility include the management of a number of social and welfare allowances, of junior high school (collège) buildings and technical staff, and local roads and school and rural buses, and a contribution to municipal infrastructures. Local services of the state administration are traditionally organised at departmental level, where the prefect represents the government; however, regions have gained importance since the 2000s, with some department-level services merged into region-level services.

The departments were created in 1790 as a rational replacement of Ancien Régime provinces with a view to strengthen national unity; the title "department" is used to mean a part of a larger whole. Almost all of them were named after physical geographical features (rivers, mountains, or coasts), rather than after historical or cultural territories, which could have their own loyalties. The division of France into departments was a project particularly identified with the French revolutionary leader the Abbé Sieyès, although it had already been frequently discussed and written about by many politicians and thinkers. The earliest known suggestion of it is from 1665 in the writings of d'Argenson. They have inspired similar divisions in many countries, some of them former French colonies. The 1822 territorial division of Spain (reverted due to the 1823 French intervention ending the trienio liberal) and the 1833 territorial division of Spain, which forms the basis of the present day Provinces of Spain with minor modifications is also based on the French model of departments of roughly equal size.Most French departments are assigned a two-digit number, the "Official Geographical Code", allocated by the Institut national de la statistique et des études économiques (Insée). Overseas departments have a three-digit number. The number is used, for example, in the postal code, and was until recently used for all vehicle registration plates. Residents commonly use the numbers to refer to their own department or a neighbouring one, for example, inhabitants of Loiret may refer to their department as "the 45". More distant departments are generally referred to by their names, as few people know the numbers of all the departments.

In 2014, President François Hollande proposed to abolish departmental councils by 2020, which would have maintained the departments as administrative divisions, and to transfer their powers to other levels of governance. This reform project has since been scrapped.