The United Kingdom of Great Britain and Northern Ireland (the UK) occupies most of the territory of the British Isles. It consists of four main parts: England, Scotland, Wales and Northern Ireland. The UK is a small country with an area of some 244,100 square kilometres. The population of the United Kingdom is over 57 million people. The official language of the United Kingdom is English. The UK is a highly developed industrial country. In law, Head of the State is Queen. In practice, the country is ruled by the elected government with the Prime Minister at the head. There are three main political parties in Great Britain: the Labour, the Conservative and the Liberal parties. The flag of the United Kingdom, known as the Union Jack.