The United Kingdom of Great Britain and Northern Ireland (usually shortened to the United Kingdom, or the UK) is a country of north-western Europe; one of two sovereign states of the British Isles, the other being the Republic of Ireland. It shares a land border with the Republic of Ireland and is otherwise surrounded by the North Sea, the English Channel, the Celtic Sea, the Irish Sea, and the Atlantic Ocean.|
The United Kingdom, often confusingly referred to as "Britain", is a constitutional monarchy and a "unitary state", composed by the political union of four constituent entities: the three constituent countries of England, Scotland, and Wales on the island of Great Britain, and the province of Northern Ireland on the island of Ireland. The UK has several overseas territories, including Gibraltar and the Falkland Islands, and has sovereignty over the Crown dependencies of the Isle of Man and the Channel Islands. The UK has close relationships with the fifteen other Commonwealth Realms, which share the same monarch as head of state.
The UK has a highly developed economy, the fourth-largest in the world. It is one of the more populous member states of the European Union and a founding partner of both the UN (with a permanent seat on the Security Council) and NATO. The UK is also one of the major nuclear weapon states.