The United Kingdom of Great Britain and Northern Ireland (the United Kingdom or the UK) is a constitutional monarchy comprising much of the British Isles.
This Union is more than 300 years old and comprises four constituent nations: England, Scotland, Wales, and Northern Ireland. It occupies all of the island of Great Britain, the north-eastern portion of the island of Ireland and most of the remaining British Isles. The UK is an island nation, but shares a open land border with Ireland. It neighbours several countries by sea, including France, Belgium, the Netherlands, Germany, Portugal, Spain, Denmark, Norway, Sweden, the Faroe Islands and Iceland.
The UK today is a diverse patchwork of native and immigrant cultures, possessing a fascinating history and dynamic modern culture, both of which remain hugely influential in the wider world. Although Britannia no longer rules the waves, the UK is still an overwhelmingly popular destination for many travellers. Its capital and largest city of London is, along with New York, often reckoned to be one of only two cities of truly global importance but many come to see quaint villages and the beautiful and quickly changing countryside.
The ‘Great’ in Great Britain (Britannia Major in Roman times; Grande-Bretagne in French) is to distinguish it from the other, smaller “Britain”: Brittany (Britannia Minor; Bretagne) in northwestern France.
However, for a geographer “Great Britain” (“GB”) refers just to the single largest island in the British Isles that has most of the land area of Scotland, England and Wales. In normal usage it is a collective term for all those three nations together. Great Britain became part of the United Kingdom when the Irish and British parliaments merged in 1801 to form the “United Kingdom of Great Britain and Ireland”.
This was changed to “… and Northern Ireland” when all but the six Northern Irish counties seceded from the Union in 1922 after a treaty granting Irish home rule. “Britain” is simply another name for the United Kingdom, and does include Northern Ireland, despite common misconceptions otherwise.