The movie was written by Damon and Affleck and directed by Gus Van Sant. The widely-spread rumor that "Good Will Hunting" was written by legendary screenwriter William Goldman was refuted in Goldman's book Which Lie Did I Tell? More Adventures In The Screen Trade as a joke that got out of hand.
It won Academy Awards for Best Actor in a Supporting Role (Robin Williams) and Best Writing, Screenplay Written Directly for the Screen. It was nominated for Best Actor in a Leading Role (Matt Damon), Best Actress in a Supporting Role (Minnie Driver), Best Director, Best Film Editing, Best Music, Original Dramatic Score, Best Music, Song (Elliott Smith for Miss Misery) and Best Picture.
Plot Summary - wikipedia contains spoilers
Will and Chuckie hang out together with their friends, drinking and fighting in Southie. Will works as a janitor at MIT, suppressing his talent for memorizing books in a single, page-at-glance reading and solving arcane math puzzles that baffle grad students until his 21st year, when his life suddenly changes.
Will and his friends pick a fight with a gang harassing a girl on the street, but Will resists arrest when the cops come and faces jail time. The judge says, "You hit a cop, you're going in."