Riley Andersen is born in Minnesota. Within her mind's Headquarters, five personifications of her basic emotions — Joy, Sadness, Fear, Disgust, and Anger — come to life and influence her actions via a control console. As she grows up, her experiences become memories, stored in colored orbs, which are sent into long-term memory each night. Her five most important "core memories" (all happy ones) are housed in a hub; each powers an aspect of her personality which takes the form of floating islands. Joy acts as a de facto leader, and since she and the other emotions do not understand Sadness' purpose, she tries to keep Sadness away from the console. Read more on Wikipedia.