Photographic film
Exposed and developed photographic film may be encountered as a file format either in negative -- a color-reversed state from which prints may be produced on photographic paper -- or as a transparency that can be viewed directly (with the naked eye, or more typically, with backlighting and magnification) or projected with a projector. The primary identification of photographic film formats is by size.
Photographic film is encountered in still formats (typically, a single image) and movie formats (strips of film transparencies with numerous sequential images designed for the projection of moving pictures). Some movie formats designed for exhibition also encode audio data (soundtracks) on film alongside the sequential images. Other movie formats were intended for exhibition with simultaneous audio provided by a synchronized separate recording.
References
Photographic film at Wikipedia
Sound film at Wikipedia
