The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain is a sovereign country in north-western Europe. The total area of the United Kingdom is 93,628 square miles (242,500 km2), with an estimated population in 2020 of over 67 million. London is the capital and largest city of England and the United Kingdom. London's 2018 population was 8,961,989.