Countries
What is a capital?
A capital is the city where a country's government sits. It is often, but not always, the largest city. Canberra is the capital of Australia although Sydney is far larger, and the capital of Turkey is Ankara, not Istanbul.
Countries with more than one capital
Some countries divide the work of government between cities. In this data: Caribbean Netherlands (Kralendijk, Oranjestad, The Bottom); South Africa (Pretoria, Bloemfontein, Cape Town).
Places with no capital
A few entries have no capital because no one governs from there or lives there permanently, for example Antarctica.