There are six types of elections in the United Kingdom: elections to the House of Commons of the United Kingdom, elections to devolved parliaments and assemblies, elections to the European Parliament, local elections, mayoral elections and Police and Crime Commissioner elections. Within each of those categories, there may be by-elections as well as general elections. Elections are held on Election Day, which is conventionally a Thursday. Since the passing of the Fixed-term Parliaments Act 2011 for general elections, all six types of elections are held after fixed periods, though early elections to parliament and the devolved assemblies and parliaments can occur in certain situations. Currently, six electoral systems are used: the single member plurality system (first past the post), the multi member plurality system, party-list proportional representation, the single transferable vote, the additional member system and the supplementary vote.
Elections are administered locally: in each lower-tier local authority, the polling procedure is operated by the Acting Returning Officer or Returning Officer, and the compiling and maintenance of the electoral roll by the Electoral Registration Officer (except in Northern Ireland, where the Electoral Office for Northern Ireland assumes both responsibilities). The Electoral Commission sets standards for and issues guidelines to Returning Officers and Electoral Registration Officers, and is responsible for nationwide electoral administration (such as the registration of political parties and directing the administration of national referendums).