A camera s viewfinder actually shows (and records on film stock) a greater area of the scene than will appear in the final product. Markings are etched in the viewfinder to indicate to the camera operator the extents of the viewable film (called the live area). An area beyond that (called the safe area) is also marked; it is in this area that the production sound mixer might direct the boom operator to place the boom microphone.imdbmovieterminology
In a television image designed for broadcast, the area into which it is considered permissable to place material, graphics, text or action so it will be viewable when received at home. Began with 4:3 aspect ratio screens because overscanning was used to avoid showing the black surrounding the active picture.