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.
The United Kingdom of Great Britain and Ireland was established on 1 January 1801 under the terms of the Acts of Union 1800, by which the nominally separate kingdoms of Great Britain and Ireland were united. In 1922, twenty-six of thirty-two counties of Ireland seceded to form the Irish Free State (later becoming the Republic of Ireland) and, to reflect the change in the United Kingdom's boundaries, the Royal and Parliamentary Titles Act 1927 formally amended the name of the UK Parliament to the "Parliament of the United Kingdom of Great Britain and Northern Ireland".
The country was renamed the "United Kingdom of Great Britain and Northern Ireland" - its formal name at present.