This meant that the United Kingdom created in 1707 by the Treaty of Union between England and Scotland encompassed all of Great Britain.The Kingdom of Ireland merged with this state in 1801 to form the United Kingdom of Great Britain and Ireland.The term "United Kingdom" is found in informal use during the 18th century and the country was also occasionally referred to as the "United Kingdom of Great Britain" though its full official name, from 1707 to 1800, was merely "Great Britain", without a "long form".
The 1707 Acts of Union declared that the kingdoms of England and Scotland were "United into One Kingdom by the Name of Great Britain", though the new state is also referred to in the Acts as the "Kingdom of Great Britain", "United Kingdom of Great Britain" and "United Kingdom".
The UK is a constitutional monarchy with a parliamentary democracy.
Other major urban areas in the UK include the conurbations centred on Birmingham, Leeds, Glasgow, Liverpool and Manchester.
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-south-west, giving it the 12th-longest coastline in the world.
The Irish Sea lies between Great Britain and Ireland.