However, the term "United Kingdom" is only found in informal use during the 18th century and the country was only occasionally referred to as the "United Kingdom of Great Britain"—its full official name, from 1707 to 1800, being merely "Great Britain", without a "long form".
The Acts of Union 1800 united the Kingdom of Great Britain and the Kingdom of Ireland in 1801, forming the United Kingdom of Great Britain and Ireland.
These are the remnants of the British Empire which, at its height in the 1920s, encompassed almost a quarter of the world's land mass and was the largest empire in history.
British influence can be observed in the language, culture and legal systems of many of its former colonies.
The Irish Sea lies between Great Britain and Ireland.
Other major urban areas in the United Kingdom include the conurbations centred on Birmingham, Leeds, Glasgow, Liverpool and Manchester.
The United Kingdom consists of four countries—England, Scotland, Wales and Northern Ireland.
Additionally, the United Kingdom's Olympic team competes under the name "Great Britain" or "Team GB".
The adjective "British" is commonly used to refer to matters relating to the United Kingdom.