A realization is the moment when you suddenly understand something clearly that you didn't grasp before. It's that “aha!” feeling when pieces fall into place and you finally get it. You might have a realization halfway through a mystery novel when you suddenly figure out who the culprit is. Or you might have the disappointing realization that you left your homework on the kitchen table just as the bus pulls away from your house.

Realizations often come unexpectedly. You might be working on a difficult math problem for twenty minutes, feeling stuck, when suddenly you have a realization about how to solve it. Sometimes realizations are small: the realization that your friend was only joking, not actually upset. Other times they're bigger: the realization that you need to change your approach to studying, or that someone you admired isn't as wonderful as you thought.

The word also means making something real or actually doing it. An architect might talk about the realization of her vision when her building design finally gets constructed. A musician experiences the realization of a dream when she performs at Carnegie Hall. In this sense, realization means taking something from imagination or planning and bringing it into actual existence.