Subdivisions of the United Kingdom

The administrative geography of the United Kingdom is complex, multi-layered and non-uniform. The United Kingdom, a sovereign state to the northwest of continental Europe, consists of England, Northern Ireland, Scotland and Wales. For local government in the United Kingdom, England, Northern Ireland, Scotland and Wales each have their own system of administrative and geographic demarcation. Consequently, there is "no common stratum of administrative unit encompassing the United Kingdom".

Because there is no written document that comprehensively encompasses the British constitution, and owing to a convoluted history of the formation of the United Kingdom, a variety of terms is used to refer to its constituent parts, which are sometimes called the four countries of the United Kingdom. The four are sometimes collectively referred to as the Home Nations, particularly in sporting contexts. Although the four countries are important for legal and governmental purposes, they are not comparable to administrative subdivisions of most other countries.

Historically, the subnational divisions of the UK have been the county and the ecclesiastical parish, whilst following the emergence of a unified parliament of the United Kingdom, the ward and constituency have been pan-UK political subdivisions. More contemporary divisions include Lieutenancy areas and the statistical territories defined with the modern NUTS:UK and ISO 3166-2:GB systems.

...
Wikipedia