The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a sovereign state in Europe. Lying off the north-western coast of the European mainland, the country includes the island of Great Britain—a term also applied loosely to refer to the whole country—the north-eastern part of the island of Ireland and many smaller islands. Northern Ireland is the only part of the UK that shares a land borderwith another state (the Republic of Ireland). Apart from this land border, the UK is surrounded by the Atlantic Ocean, with the North Sea to its east, the English Channel to its south and the Celtic Sea to its south-southwest. TheIrish Sea lies between Great Britain and Ireland. The UK has an area of 93,800 square miles (243,000 km2), making it