In North-Western Europe, the United Kingdom of Great Britain and Northern Ireland, usually referred to as the United Kingdom (UK) or Britain, is a sovereign nation located off the north-western coast of the European continent. Located in the British Isles, the United Kingdom consists of the island of Great Britain, the northern-eastern portion of the island of Ireland, and a number of smaller islands. Northern Ireland and the Republic of Ireland are separated by a land frontier. On the rest of its borders, the United Kingdom is encircled by the Atlantic Ocean, which it shares with the North Sea on its eastern border, the English Channel on its southern border, and The Celtic Sea on its southern border, giving it the 12th-longest coastline in the world. Great Britain and Ireland are separated by the Irish Sea. 93,628 square miles (93,628 square kilometres) is the entire land area covered by the United Kingdom (242,500 km2).
The United Kingdom is a unitary parliamentary democracy with a constitutional monarchy as its constitutional foundation. Queen Elizabeth II was the queen of the United Kingdom since 1952. The capital and biggest city is London, which is a worldwide metropolis and financial centre with a population of 10.3 million people in the metropolitan region. The United Kingdom is made up of 3 countries: England, Scotland, Wales, and Northern Ireland, all of which are members of the European Union. Aside from the United Kingdom, each of the component nations has its own devolved government, each with a different set of competences.
Members of the Commonwealth of Nations, the Council of Europe, the G7, the Group of Ten, the G20, and the United Nations, as well as the Organization for Economic Co-operation and Development (OECD), Interpol, and the World Trade Organization, are all represented in the British delegation to these organisations (WTO). During the period 1973 to 2020, it was a member state of the European Communities (EC) and its successor, the European Union (EU), having joined in 1973 and voting in a referendum in 2016. It withdrew from the EU in 2020 after a referendum in 2016.