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 border with another state (the Republic of Ireland). Apart from this land border, the UK is surrounded by the Atlantic Ocean to its west and north, the North Sea to its east and the English Channel to its south. The Irish Sea lies between Great Britain and Ireland.