The process of winding the film from the take-up reel to the supply reel so that the head end, or start of the reel, is on the outside. If there are no identifying leaders on the film, upside-down images will signify the head end.
The process of retracting a roll of exposed film into its cassette before removal from the camera. Motorized on many models, rewinding starts automatically at the end of the roll or when you press the midroll rewind button.