The United Kingdom (full title The United Kingdom of Great Britain and Northern Ireland but usually shortened to the United Kingdom, the UK, or Britain) is a country and sovereign state to the northwest of mainland Europe.
It comprises the island of Great Britain, the north-east part of the island of Ireland and many small local 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 waters of the Atlantic Ocean, the North Sea, the English Channel, and the Irish Sea. It is linked to France by the Channel Tunnel.