A constituent is a voting member of a community or organization and has the power to appoint or elect. A constituency is all of the constituents of a representative. Constituents also have the power to remove their representative from the position to which they have appointed him or her. All of the constituents who are registered to vote are called the electorate.
In the United Kingdom, a parliamentary constituency is a district that elects a member of parliament. It is sometimes called a Parliamentary seat or a Division. Constituencies for local government elections are called either Wards or electoral divisions.
As of 2020, there are 650 House of Commons constituencies in the UK:
Northern Ireland has 18 constituencies, each of which elect six MLAs to the Northern Ireland Assembly under the Single Transferable Vote system.
The Scottish Parliament has 73 single-member constituencies, with the remaining 56 seats being selected by the Additional Member System (AMS). Until the passage of the Scottish Parliament (Constituencies) Act 2004, the constituencies of the Scottish Parliament were identical to those of the House of Commons.
The National Assembly for Wales has 40 constituencies which are identical to the Welsh constituencies of the House of Commons. Its remaining 20 seats are selected by AMS.
The London Assembly has 14 single-member constituencies. Its remaining 11 seats are selected by AMS.
The United States House of Representatives has 435 constituencies called "Congressional districts" each electing one member.
The term "constituency" is usual in many countries, especially in members of the Commonwealth of Nations.