Which countries are on the list of 1st world countries?
There is no official list of First World Countries, as today the meaning of “First World” has numerous definitions. If you define “First World” by the original members of NATO and nations affiliated with it then you would include these countries:
Spain (since 1982)
This is a relatively limited list as you could also include many other nations such as South Africa, the Arab Emirates, Russia, and numerous others. In general, a First World country is a nation that is either fully developed or has a centralized and industrialized society.