Why 195 is the number
The count people argue about comes down to who is doing the counting. The United Nations has 193 member states. It also recognises two permanent observer states that are not members: the Holy See, which governs Vatican City, and the State of Palestine, granted observer status by the General Assembly in November 2012. Add those two and you get 195, which is the list this quiz uses and the list the Geography app uses.
Everything above that number is contested. Taiwan governs itself and is not a UN member. Kosovo is recognised by many states and not by others. Western Sahara, the Cook Islands and Niue each sit in their own category. A quiz has to pick one line and hold it, so this one holds the UN line. The longer version of that argument lives in how many countries are in the world.
How the countries of the world quiz works
Type a name and press Enter, or just keep typing: a name that cannot grow into another country is accepted the moment it is complete. Spelling is forgiving. Accents, hyphens, apostrophes, a leading "the", and the difference between "and" and "&" are all ignored, so "cote divoire" and "Côte d'Ivoire" both land. Common alternates work too: Holland for the Netherlands, Burma for Myanmar, Swaziland for Eswatini, UAE for the United Arab Emirates.
One deliberate exception. A word claimed by two states resolves to neither. "Congo" is the clearest case: the Republic of the Congo and the Democratic Republic of the Congo are different countries, so the quiz waits for you to say which. It is the only name in the set that does this: "Korea", "Guinea" and "Sudan" each resolve to one country and are accepted.
The timer is optional and off by default. Fifteen minutes is the traditional target, but nothing about this page forces a clock on you. Press Start to begin, press it again to pause, and your best score is kept on this device only.
Name all the countries in Europe, or in Africa
Most people who want the continents want them one at a time, because a continent is a chunk you can actually hold in your head. The board on this page is grouped into Africa, Asia, Europe, North America, South America and Oceania, with a live count beside each heading, so you can play the whole world and still read it as six smaller runs. Watching Europe reach 44 of 44 while South America sits at 5 of 12 tells you more than one total ever does.
Africa has its own page, because it is the continent almost everyone underestimates: name all 54 countries in Africa. If you want capitals instead of names, the world capitals quiz takes the same list from the other side.