Specifically, a constituency often refers to the group or area from which voters in an election are drawn. Depending on the electoral system being used, a constituency may elect one or more members. Each constituency in the United Kingdom now elects one member, though some used to elect more than one. Constituencies in the Republic of Ireland elect between 3 and 5 TDss, while constituencies between 1536 and 1800 in the Kingdom of Ireland used to return 2 MPs. Northern Ireland constituencies elects 6 MLAs to the Northern Ireland Assembly.

In the United Kingdom a parliamentary constituency is sometimes called a Parliamentary seat or a Division. Constituencies for local government elections are called Wards. MPs elected in the UK general election, 2001 includes the constituencies as they stood at the last general election.

A marginal constituency is one where the margin between the expected voting for the major parties in an election is slim. In United Kingdom general elections, the voting in a relatively small number of marginal constituencies usually determines the outcome of the entire election.

In the United States, electoral constituencies are known as Districts.