This is a list of the counties of the United Kingdom. The history of local government in the United Kingdom differs between England, Northern Ireland, Scotland and Wales, and the subnational divisions within these which have been called counties have varied over time and by purpose. The county has formed the upper tier of local government over much of the United Kingdom at one time or another, and has been used for a variety of other purposes, such as for Lord Lieutenants, land registration and postal delivery. This list is split by constituent country, time period and purpose.