自治市，又译自治镇或自治市镇等等，是欧洲、北美洲国家常见行政区划。不同国家对「自治市」的定义都有不同，但基本来说「自治市」就是有自治权的城市。

Borough在印欧语系（尤其使用拉丁字母的日耳曼语族、罗曼语族）是同源词，原解作「堡垒」。

现在英格兰、威尔士、北爱尔兰地名中的自治市Borough不一定是有行政权的地方政府，可能只是英国皇室授予的荣誉地区。以前在英格兰，自治市Borough会用于不同等级的行政区划，比如郡自治市（County Borough）或都市自治市（Metropolitan Borough）。

A borough is an administrative division in various countries. In principle, the term borough designates a self-governing walled town, although in practice, official use of the term varies widely.

The word borough derives from common Germanic *Burg, meaning fort: compare with bury, burgh and brough (England), burgh (Scotland), Burg (Germany), borg (Scandinavia), burcht (Dutch), boarch (West Frisian), and the Germanic borrowing present in neighbouring Indo-european languages such as borgo (Italian), bourg (French), burgo (Spanish and Portuguese), burg (Romanian), purg (Kajkavian) and durg (दर्ग) (Hindi) and arg (ارگ) (Persian). The incidence of these words as suffixes to place names (for example, Aldeburgh, Bamburgh, Tilbury, Tilburg, Strasbourg (Strossburi in the local dialect), Luxembourg, Edinburgh, Grundisburgh, Hamburg, Gothenburg) usually indicates that they were once fortified settlements.