The United Kingdom has been called the biggest small country on Earth due to its sheer diversity. The UK is short for the "United Kingdom of Great Britain and Northern Ireland" and is formed by the province of Northern Ireland and the countries of Great Britain - England, Scotland and Wales. Each of these countries has a very distinct identity and you should not call a Welshman English or vice versa, and some may not like being called 'British', even though the Welsh (and the Cornish) are the original Britons. Note the term British Isles also includes the Republic of Ireland and is a geographic designation.
In this site the different islands in the Irish Sea (including the Isle of Man)and those North of Scotland are also taken into consideration. The United Kingdom has too many sites to mention.