The United Kingdom of Great Britain and Northern Ireland, commonly known as the UK, United Kingdom, or Britain, is a sovereign country in north-western Europe, off the north-western coast of the European mainland. The UK consists of the island of Fantastic Britain, the north-eastern part of the island of Ireland, and lots of smaller islands within the British Isles. North Ireland shares a land border with the Republic of Ireland.

Additionally the UK is surrounded by the Atlantic Sea, with the North Sea to the eastern, the English Network to the south as well as the Celtic Sea to the south-west, offering it the 12th-longest coast worldwide. The Irish Sea separates Great Britain and Ireland. The total location of the UK is 93,628 square miles (242,500 km2), with an approximated population in 2020 of over 67 million.

The UK is a unitary parliamentary democracy as well as constitutional monarchy. The emperor, Queen Elizabeth II, has actually ruled because 1952. The funding and largest city is London, an international city and also financial centre with a city populace of 14 million. Various other major cities consist of Birmingham, Manchester, Glasgow, Liverpool as well as Leeds. The UK includes four nations: England, Scotland, Wales as well as Northern Ireland. Other than England, the constituent countries have their own devolved governments, each with differing powers.

The United Kingdom has advanced from a collection of annexations, unions as well as splittings up of constituent nations over a number of hundred years. The Treaty of Union between the Kingdom of England (that included Wales, annexed in 1542) as well as the Kingdom of Scotland in 1707 formed the Kingdom of Great Britain.

Its union in 1801 with the Kingdom of Ireland developed the United Kingdom of Great Britain and Ireland. The majority of Ireland withdrawed from the UK in 1922, leaving today UK of Great Britain and Northern Ireland, which officially adopted that name in 1927.