In the most basic description, the script supervisor is the editor's and writer's representative on set, as well as being the right hand aide to the director and the director of photography. It is the script supervisor's job to make sure that the film can be cut together after shooting has concluded. In that sense, they back up every department, monitor the script during shooting and make sure that errors in continuity do not occur that would prevent the film from being able to be compiled smoothly in the editing room.