United Kingdom

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,  is a sovereign country located off the north-western coast of the European mainland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, and many smaller islands. Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state, the Republic of Ireland. Apart from this land border, the United Kingdom is surrounded by the Atlantic Ocean, with the North Sea to the east, the English Channel to the south and the Celtic Sea to the south-west. The Irish Sea separates Great Britain and Ireland. The United Kingdom's 242,500 square kilometers (93,600 sq mi) were home to an estimated 56.0 million inhabitants in 1971.

The United Kingdom is a unitary parliamentary democracy and constitutional monarchy. The current monarch is Queen Elizabeth II, who has reigned since 1952, making her the world's longest-serving current head of state. The United Kingdom's capital and largest city is London, a global city and financial center with an urban area population of 10.3 million. Other major cities include Birmingham, Manchester, Glasgow, Leeds and Liverpool.

The United Kingdom consists of four constituent countries: England, Scotland, Wales, and Northern Ireland. Their capitals are London, Edinburgh, Cardiff, and Belfast, respectively.