A county is a geographical region of a country used for administrative or other purposes in certain modern nations. The term is derived from the Old French conté or cunté denoting a jurisdiction under the sovereignty of a count (earl) or a viscount. Literal equivalents in other languages, derived from the equivalent of "count", are now seldom used officially, including comté, contea, contado, comtat, condado, Grafschaft, graafschap, and zhupa in Slavic languages; terms equivalent to English language administrative terms such as municipality, district, circuit and commune/community are now often instead used.
When the Normans conquered England, they brought the term with them. The Saxons had already established the districts that became the historic counties of England, calling them shires; many county names derive from the name of the county town (county seat) with the word shire added on: for example, Gloucestershire and Worcestershire. The Anglo-Saxon terms earl and earldom were taken as equivalent to the continental terms "count" and "county" under the conquering Normans, and over time the two blended and became equivalent. Further, the later-imported term became a synonym for the native Old English word sċīr ([ʃiːr]) or, in Modern English, shire – an equivalent administrative division of the kingdom. The term "county" evolved, consequently, to designate a level of local administration that was immediately beneath a national government, within a unitary (non-federal) system of government. County later also became used differently in some federal systems of government, for a local administrative division subordinate to a primary subnational entity, such as a Province (e.g. Canada) or a State (e.g. the United States); in these countries, a county is a level 3 territorial unit (NUTS 3).
In the United States and Canada, founded 600 years later on the British traditions, counties are usually an administrative division set by convenient geographical demarcations, which in governance have certain officeholders (for example sheriffs and their departments) as a part of the state and provincial mechanisms, including geographically common court systems.
A county may be further subdivided into districts, hundreds, townships or other administrative jurisdictions within the county. A county usually, but not always, contains cities, towns, townships, villages, or other municipal corporations, which in most cases are somewhat subordinate or dependent upon county governments. Depending on the nation, municipality, and local geography, municipalities may or may not be subject to direct or indirect county control — the functions of both levels are often consolidated into a city government when the area is densely populated.
Outside English-speaking countries, an equivalent of the term county is often used to describe subnational jurisdictions that are structurally equivalent to counties in the relationship they have with their national government; but which may not be administratively equivalent to counties in predominantly English-speaking countries.