The United Kingdom of Great Britain and Northern Ireland (commonly known as the United Kingdom, the UK or Britain) is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of the island of Ireland, and many small islands. Northern Ireland is the only part of the UK with a land border, sharing it with the Republic of Ireland. Apart from this land border, the UK is surrounded by the Atlantic Ocean, the North Sea, the English Channel and the Irish Sea. The largest island, Great Britain, is linked to France by the Channel Tunnel.
The United Kingdom is a constitutional monarchy and unitary state consisting of four countries: England, Northern Ireland, Scotland and Wales. It is governed by a parliamentary system with its seat of government in London, the capital, but with three devolved national administrations of varying powers in Belfast, Cardiff and Edinburgh, the capitals of Northern Ireland, Wales and Scotland respectively. The Channel Island bailiwicks of Jersey and Guernsey, and the Isle of Man are Crown Dependencies, which means they are constitutionally tied to the British monarch but are not part of the UK. The UK has fourteen overseas territories, all remnants of the British Empire, which at its height in 1922 encompassed almost a quarter of the world's land surface, the largest empire in history. British influence can still be observed in the language, culture and legal systems of many of its former colonies.