Microform is a name given to special photographic films. Microforms contain reduced images of documents. Usually, documents stored on microform are reduced about 25 times. Microform is mainly used for archival purposes.
There are three common formats:
- Microfilm, which comes in reels of film.
- Aperture card, This contains additional digital data (as a punch card).
- Microfiche, a flat sheet with many pages.
Properly stored (room temperature, 50% humidity), microform should be able to last up to 500 years.