In an era of digitization, NARA continues to microfilm records because microfilm is a low-cost, reliable, long-term, standardized image storage medium. The equipment needed to view microfilm images is simple, consisting of light and magnification. The medium has a life-expectancy of hundreds of years.
Digital images, on the other hand, consist of a wide variety of machine codes that require computer hardware and software to be made visible. To avoid the obsolescence of changing computer technology, digital images must be reformatted periodically.
The cost of maintaining microfilm is small compared with that of digital images. Microfilm only needs shelving in a cool, dry place for a very long period of time.
NARA has some holdings in which a few records are referenced often enough to cause wear and tear. Such records are candidates for microfilming. Most records are not used often enough to justify microfilming.
NARA has microfilmed millions of pages of permanently valuable Federal records. For information on what records have been microfilmed, see the listing of NARA microfilm catalogs.
Digital images may prove valuable for immediate access to facilitate the delivery of frequently requested items. NARA is committed to keeping up with digital technology and applying it experimentally as can be seen by viewing NARA's National Archives Catalog.