Administrative divisions (also Administrative units, Administrative regions, Subnational entities, or a Constituent states (as well as many similar generic terms) are geographical areas into which a particular independent Sovereign state is divided. Such a unit usually has an administrative authority with the power to take administrative or policy decisions for its area.
Usually, Sovereign states have several levels of administrative division. The common names for the principal (largest) Administrative divisions are: States (i.e. "Subnational states", rather than Sovereign states), Provinces, Lands, Oblasts, Governorates, Cantons, Prefectures, Counties, Regions, Departments, and Emirates. These, in turn, are often subdivided into smaller administrative units known by names such as Circuits, Counties, Comarcas, Raions, Județe, or Districts, which are further subdivided into Municipalities, Communes or communities constituting the smallest units of subdivision (the Local governments).
The exact number of the levels of administrative divisions and their structure largely varies by country (and sometimes within a single country). Usually, the smaller the country is (by area or population), the fewer levels of administrative divisions it has. For example, the Vatican does not have any Administrative subdivisions and Monaco has only one level, while such countries as France and Pakistan have five levels each. The United States is composed of states, possessions, Territories, and a Federal district, each with varying numbers of subdivisions.
The Principal administrative division of a country is sometimes called the "First-level (or First-order) administrative division" or "First administrative level". Its next subdivision might be called "Second-level administrative division" or "Second administrative level" and so on. An alternative terminology is provided by Nomenclature of Territorial Units for Statistics which terms the principal division as the second level or NUTS-2.