What's the difference between Great Britain and the United Kingdom?

People often use Great Britain and the United Kingdom interchangeably? But, is there a difference?

Yes! You could think of Great Britain as a geographical reference and the United Kingdom as political.

Great Britain refers to the island on which are found the countries of England, Wales and Scotland.

The United Kingdom is all of Great Britain (for the moment depending on how the Scots vote) and Northern Ireland.

In fact, the official name of this realm over which Queen Elizabeth II reigns is called The United Kingdom of Great Britain and Northern Ireland.

Technically, if Scotland wins independence, it will still be geographically part of Great Britain, but the U.K. will have to change its name to The United Kingdom of England, Wales and Northern Ireland.