Members of the House of Commons are elected in General Elections. General Elections are called by the Prime Minister. General Elections are held at least once every five years. The maximum term that a parliament can exist before a new election interrupts it is defined by parliament. Currently, the Parliament Act states that five years is the maximum length.
From 2007 Scotland will use Single Transferable Vote to elect all of its local councillors. England and Wales use first past the post or multiple-member first past the post for local elections. Northern Ireland uses STV for its local elections.
Members of the European Parliament for Northern Ireland are elected using Single Transferable Vote (STV). MEPs for England, Scotland and Wales are elected using the D'Hondt method.