What does Sulley do in the factory of Monsters Inc. movie?

In the movie Monsters Inc., Sulley works as a scarer. His job is to go into children's bedrooms at night and scare them so that they can collect their screams. These screams are then used to power the city of Monstropolis, where all of the monsters live. Sulley is very good at his job, and he is one of the top scarers in the company.