In the United Kingdom (UK), each of the electoral areas or divisions called constituencies elects one or more members to a parliament or assembly.
Within the United Kingdom there are now five bodies with members elected by constituencies and one that was abolished:
Electoral areas called constituencies are also used in elections to the European Parliament. (See European Parliament constituencies.)
In local government elections, electoral areas are called wards or electoral divisions.

The House of Commons (see United Kingdom Parliament constituencies)
The Northern Ireland Parliament (see List of Northern Ireland Parliament constituencies)
The Scottish Parliament (see Scottish Parliament constituencies and regions)
The Northern Ireland Assembly (see Northern Ireland Assembly constituencies)
The National Assembly for Wales (see National Assembly for Wales constituencies and regions)
The London Assembly (see London Assembly constituencies) County constituencies and borough constituencies
As of the 2005 United Kingdom general election, the House of Commons has 646 constituencies covering the whole of the United Kingdom. Each constituency elects one Member of Parliament (MP) by the first past the post system of election.
The House of Commons is one of the two legislative bodies of the Parliament of the United Kingdom, the other being the House of Lords.

House of Commons constituencies

List of Parliamentary constituencies in the United Kingdom
Former United Kingdom Parliament constituencies
Constituencies in the next United Kingdom general election
University constituency See also
There are fourteen London Assembly constituencies covering the Greater London area, and each constituency elects one member of the assembly by the first past the post system of election. Also, eleven additional members are elected from Greater London as a whole to produce a form or degree of mixed member proportional representation.
Constituency names and boundaries remain now as they were for the first general election of the assembly, in 2000.
The assembly is part of the Greater London Authority and general elections of the assembly are held at the same time as election of the Mayor of London.

London Assembly constituencies

Northern Ireland Assembly constituencies
Scottish Parliament constituencies are sometimes called Holyrood constituencies, to distinguish them from Westminster (House of Commons) constituencies. The Scottish Parliament Building is in the Holyrood area of Edinburgh, while the main meeting place of the Parliament of the United Kingdom is the Palace of Westminster, in the City of Westminster.
There are 73 Holyrood constituencies covering Scotland, and each elects one Member of the Scottish Parliament (MSP) by the first past the post system of election. Also, the constituencies are grouped into eight electoral regions, and each of these regions elects seven additional members, to produce a form or degree of mixed member proportional representation.
The existing constituencies were created, effectively, for the first general election of the Scottish Parliament, in 1999. When created, all but two had the names and boundaries of Westminster constituencies. The two exceptions were the Orkney Holyrood constituency, covering the Orkney Islands council area, and the Shetland Holyrood constituency, covering the Shetland Islands council area. For Westminster elections, these council areas were covered (and still area covered) by the Orkney and Shetland Westminster constituency.
In 1999, under the Scotland Act 1998, which enabled the creation of a new set of Westminster constituencies without change to Holyrood constituencies. The new Westminster boundaries became effective for the United Kingdom general election, 2005.