Earlier this month, RD said something like, "Did you know that part of Ireland (Northern Ireland) is in the United Kingdom but that another part (the Republic of Ireland) is not, and that Great Britain is comprised of several countries that are part of the UK?"
I had never really bothered to learn the geographic details of this matter although I did wonder why England and Ireland share the same country code (+44) even if they were different countries. I knew that GBP is the SWIFT code for the pound sterling but wasn't sure which countries aside from England used this. And up until RD mentioned it, in my mind the UK and Great Britain were interchangeable terminologies. (Am sure London Eye would have promptly showed me the error of my ways.)
RD continued to rattle away countries and subsets of countries belonging to Great Britain, the United Kingdom, the British Isles, etc. that were beyond my mental comprehension so I said, "You have to send me a Venn Diagram."
He gave me something better, he shared me this link, which was really informative.
In a nutshell (or if you don't have the patience to watch the video), this illustrates what goes where.
May I just say that I am glad I don't have to take geography tests anymore.