What does decolonization mean and how did new nations gain independence?

For a long stretch of history, a handful of countries did something extraordinarily bold and unfair: they claimed faraway lands as their own. A map of the world in 1914 looks like a board game where just a few players own almost every square. This is called colonialism — one country ruling another from across an ocean. So here's the big question: how did all those colored-in squares become the free countries we know today?
First, the word. "Decolonization" sounds enormous, but break it apart and it's friendly. "Colonization" is the taking. The little prefix "de-" means undoing it. So decolonization is simply the great undoing — the long, messy, hopeful process of colonized peoples taking their own countries back into their own hands.
