A department (French: département, Spanish: departamento) is an administrative or political division in several countries. Departments are the first-level divisions of 11 countries, nine in the Americas and two in Africa. An additional 10 countries use departments as second-level divisions, eight in Africa, and one each in the Americas and Europe.

As a territorial entity, "department" was first used by the French Revolutionary governments, apparently to emphasize that each territory was simply an administrative sub-division of the united sovereign nation. (The term "department", in other contexts, means an administrative sub-division of a larger organization.) This attempt to de-emphasize local political identity contrasts strongly with countries divided into "states" (implying local sovereignty).

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 1764 in the writings of d'Argenson.

Today, departments may exist either with or without a representative assembly and executive head depending upon the countries' constitutional and administrative structure.