Originally Posted by
Misco60
A bigger question is that of what actually counts as a country or territory. Jersey, Guernsey, Isle of Man? I think so. Greenland? Possibly. Svalbard? The app I use to keep track of my travels says so, but I'm not so sure. And what about countries that no longer exist? I don't count them, but perhaps I should. It's just a bit of fun, and I don't take it too seriously.

IIRC we used the CIA fact-book, which listed every country, territory and dependency in the world. But there may be a more accurate source nowadays. Maybe the UN publishes one?