The master shot provides an overview of the entire scene, and is usually, but not always, a wide shot.  It typically opens the scene, and is designed to provide the audience with a mental map of where actors and props are positioned in a scene, and relative to each other. A master shot may, on occasion, double as the establishing shot as well, but not commonly. The master shot should cover all relevant characters in the scene, and typically follows the establishing shot in opening the scene, but may be cut back to at any point in the flow of the edits.