Script Supervisor

What is the role of the script supervisor in a film production?  What are their responsibilities?

    In a film production, the role of a script supervisor is to maintain the continuity of a scene between takes and shots and take notes. The responsibilities of a script supervisor (or scripty) is to take notes on everything that is in a scene, i.e., props, costuming, actors and their body language,  and everything that can be heard. This is important as they can identify any continuity errors and correct them, preventing them from appearing in the final project. They also take notes on which take of a shot is the one that the director likes and if an actor who's speaking is visible on camera.