What is a country? Is it a place like the United States that is recognized by all other countries and is a member of the United Nations? Is it, like Kosovo, a place that is recognized by most of the world’s powers but isn’t a UN member? Where does Taiwan, which has its own government and its own military despite being claimed by China, fit? And where does all this leave places like Catalonia and Iraqi Kurdistan, many of whose citizens have voted to secede over the objections of the countries they’re currently part of?

“Really, when we’re talking about a country, we’re talking about a political territory with a population, a government, and legally recognized boundaries that indicate or grant sovereignty,” Rebecca Richards, a lecturer in international relations at Keele University in the U.K., said in an email. “They are the legally determined shapes on a map.”

But, as she pointed out, it’s a bit more complicated than drawing lines.

“We generally accept that we know that a state has sovereign recognition when it gains membership to the UN—it’s acceptance by the international community,” said Richards. And the fact is that though the UN has 193 countries it considers member states, a number nearly four times higher than it had at its founding in 1945, the overwhelming majority of new members joined in the 1950s and ’60s, when European nations shed their Asian and African colonies; and in the ’90s, following the breakup of the Soviet Union and Yugoslavia.