What is the official name of the UK?

The official name of the UK is "The United Kingdom of Great Britain and Northern Ireland." This name reflects the full composition of the country, which includes Great Britain (consisting of England, Scotland, and Wales) and Northern Ireland. The inclusion of Northern Ireland in the official name highlights its status and significance as part of the United Kingdom, distinguishing it from other territories in the British Isles.

The use of the term "British Isles" encompasses a broader geographical area, including the UK and the Republic of Ireland, but it is not the official name of the UK. Similarly, "United Kingdom" is a commonly used term that is somewhat informal and lacks the specificity of the full official title. "Great Britain" refers specifically to the largest island that includes England, Scotland, and Wales, but does not account for Northern Ireland, thus not representing the complete entity that is the UK.