Many people still use the expression "third world", I suppose schools are still teaching that, especially when the teachers themselves are of a certain age (and don't update themselves). The "first world" was supposed to be the Western/capitalist block, the "second world" the Eastern/communist block and the the rest was called "third world", "developing countries" or something similar. Since all this East-West thing has changed in the 1990s people started to use expressions like "global South", "emerging economies", "tiger states" (Asia) and similar when they refer to the former "third world".

I am interested in these kinds of topics. No need for you to feel sorry if you did use those concepts you were taught in school. We are here to learn from each other so I am happy I could give you some input today. :-)

Keep on steeming my friend!