There are several types of elections that take place in the UK: general elections are held to elect Members of Parliament who sit in the House of Commons, local elections that take place to elect local councillors for the local government, regional elections that have been held since 1999 (when devolution of power came into effect) to elect Members of the Scottish Parliament, Assembly Members to the National Assembly of Wales and Assembly Members to the Northern Ireland Assembly, as well as Assembly Members of the Greater London Assembly and the London Mayor.
The electoral systems are varied: First-Past-The-Post (FPTP), Proportional Representation (PR), Single Transferable Vote (STV), Alternative Vote (AV) and Supplementary Vote (SV). When at some point a representative dies, retires or is dismissed, a by-election takes place to fill the vacant seat.
General elections do not have fixed dates, contrary to France and the USA. The period between two general elections is 5 years unless there is a national emergency. For electoral purposes, the UK is divided in constituencies. There are 533 constituencies in England, 40 in Wales, 59 in Scotland and 18 in Northern Ireland. That number may be subject to change, as it is decided by the Boundary Commission. Each constituency returns one Member of Parliament to one seat in the House of Commons. Each constituency represents about 70,000 inhabitants, even though some may contain fewer. Cities can be divided into several constituencies called wards. For example, Greater London has 73 wards. Citizens aged 18 or more may vote. Some cannot vote: the Monarch, members of the House of Lords, people suffering from mental disorders and people serving prison sentences.
