The United Kingdom of Great Britain and Northern Ireland (usually shortened to the United Kingdom, the UK, or Britain ) is a country and sovereign state that lies to the northwest of Continental Europe with Ireland to the west. It occupies most of the British Isles and its territory and population are primarily situated on the island of Great Britain and in Northern Ireland on the island of Ireland. The United Kingdom is bounded by the Atlantic Ocean, and its ancillary bodies of water, including the North Sea, the English Channel, the Celtic Sea, and the Irish Sea. The mainland is linked to France by the Channel Tunnel, with Northern Ireland sharing a land border with the Republic of Ireland.

The United Kingdom is a political union made up of four constituent countries : England, Scotland, Wales and Northern Ireland.

The United Kingdom also has many overseas territories, including Bermuda, Gibraltar, Pitcairn Islands, British Indian Ocean Territory, Falkland Islands, and British Antarctica among others. The dependencies of the Channel Islands and the Isle of Man , formally possessions of the Crown, form a federacy with the United Kingdom collectively known as the British Islands. A constitutional monarchy, Queen Elizabeth II is also the Queen and Head of State of 15 other Commonwealth Realms such as Canada, Australia, and New Zealand.

Despite the dissolution of the British Empire and the steady decline of the UK's influence throughout the world, it remains a Great power . A member of the G8, the United Kingdom is a highly developed country with the fifth largest economy in the world and second largest in Europe, estimated at US$ 2.2 trillion. It is the third most populous state in the European Union with a population of 60.2 million and is a founding member of the North Atlantic Treaty Organisation ( NATO ) and the United Nations ( UN ), where it holds permanent membership on the Security Council. The UK is a major military power and is one of the world's five acknowledged nuclear powers.

Education and Science

The United Kingdom contains some of the world's leading, and oldest, seats of higher education, such as the ancient multi-faculty universities at Oxford and Cambridge. It has produced innumerable scholars, scientists and engineers including Sir Isaac Newton, Bertrand Russell, Adam Smith, James Clerk Maxwell, Lord Kelvin, Sir Humphry Davy, Joseph John Thomson, Sir Ronald Aylmer Fisher, Michael Faraday, Charles Darwin, Alexander Fleming, Francis Crick, Sir Joseph William Bazalgette and Isambard Kingdom Brunel; the nation is credited with numerous scientific discoveries including hydrogen, gravity, the electron, structure of DNA, antibiotics and inventions including the chronometer, steam locomotive and the modern railway, vaccination, television, electric lighting, the electric motor, the screw propeller, the internal combustion engine, the jet engine, the modern bicycle, the electronic computer, along with the later development of the World Wide Web.

In 2006, it was reported that the UK was the most productive source of research after the United States; with the UK producing 9% of the world's scientific research papers with a 12% share of citations.