Stratification does not stop at a border. Sort the planet by income per person and it falls into layers as steep as any class ladder inside a single country — except that here, the rung you are born on is decided almost entirely by where you were born. Tap a nation to see what its tier means, re-shade the map by life expectancy or child mortality to watch the ranking change, then sort eight countries by their indicators alone.
Four tiers, one world
Global stratificationtap a nation, or pick a tier
Read the map differently
Why are they unequal?
About the numbers. Income tiers follow the World Bank classification by gross national income per person (Atlas method); the other figures are recent World Bank and UN estimates, rounded. They shift year to year, and a few countries sit close enough to a threshold to cross it. Treat them as the shape of the world, not as decimals.