This is a fantastic movie and if you haven't seen it yet, do so as you will not be disappointed. The movie looks into the mind of a child and her parents. Inside the minds are characters that control specific emotions. The five detailed in this move are joy, fear, sadness, anger, and disgust. The movie does a wonderful job looking at the battle and conflict between emotions as they relate to life events.
The movie is not perfect on the science. The description of memories in the movie is not quite accurate as our memory of past events changes based on current events. There's a bit of this in the movie, but it does give a bit of a misinterpretation that your memories are stored for access at a later point. In a way they are, but how you remember events changes.
Despite this, the movie is fantastic as I've already said and you should watch it. There are a few tearjerker moments so bring a tissue!