Short answers, pulled from the story.
France has 101 departments in total. Ninety-six are in metropolitan France and five are overseas departments, which are also classified as overseas regions: French Guiana, Guadeloupe, Martinique, Réunion, and Mayotte.
The modern department system was decreed on the 26th of February 1790 by the National Constituent Assembly. The process of eliminating provincial privileges that preceded it began on the 4th of August 1789.
The naming convention was deliberate. Historical province names carried old cultural loyalties that the revolutionary government wanted to dissolve. Departments were named after physical features such as rivers, mountains, and coastlines to build a more homogeneous national identity.
Marc-René d'Argenson put forward the earliest known suggestion in 1665, proposing territorial departments as administrative areas for the Ponts et Chaussées infrastructure. The idea became particularly associated with the revolutionary leader the Abbé Sieyès by the time it was enacted in 1790.
Gironde is the largest department in area at 10,000 km2, while Paris is the smallest at 105 km2. The most populous department is Nord with 2,550,000 inhabitants, and the least populous is Lozère with 74,000.
Spain's 1833 territorial division, which forms the basis of present-day Spanish provinces with minor modifications, was directly based on the French model of departments of roughly equal size. Algeria also used the department system from 1848 until its independence in 1962, and several Caribbean and Indian Ocean territories received departmental divisions during the Napoleonic period.