basic electoral unit into which eligible electors are organized to elect representatives to a legislative or other public body. The registration of electors is also usually undertaken within the bounds of the constituency.

Constituencies vary in size and in the number of representatives elected by them. In size they may number a few thousand or be as large as the country itself. Constituencies may be represented by one or by several representatives, depending on the type of electoral system employed. All constituencies within a state should, ideally, be equal in population. To achieve this as nearly as possible, periodic alterations of boundaries are made. Constituencies are most often formed on a geographical basis, but the basis could also be occupational (for example, the university constituencies that once existed in the United Kingdom).