The House of Commons and House of Lords, with the monarch, make up Parliament.
Parliament passes laws, approves taxation and debates the major issues of the day.
The Prime Minister heads the Government and appoints ministers, about 20 of whom are in the policy-making Cabinet. Elections, in which citizens over 18 may vote by secret ballot, are held at least every five years. Voting is not compulsory. The Lords act as an upper house - a check against legislation passed in the Commons. The Labour Party won the General Election in May 1997, with 418 MPs elected - the party's largest number ever.