If you were to re-draw the map of the world according to each countries population, you would get a warped world that looked like this. Some giant countries, like Canada and Australia, become tiny strips and dots while other giant countries like China and India predictably inflate and take over the map.
You can also see how crowded some countries are, Japan is bigger than Mexico! But at least all these countries made it on the map, Iceland and Belize didn't even have enough people to show up.
The map uses one grid square to represent one million people. You can see how the map tries to stay true to a country's original shape although it obviously gets hard when you're dealing with very large or very small populations. It is, however, impressive how South America manages to maintain its original shape. [Reddit, Maps on the Web]