Bit Rot
Bit rot is the gradual, often silent degradation of digital data caused by physical media decay, hardware failure, or uncorrected errors, leaving files corrupted, unreadable, or subtly altered over time.
Bit rot is the slow corruption of stored digital information as the underlying bits on a medium degrade or are silently altered. It can stem from magnetic decay on disks and tape, charge leakage in flash storage, optical disc deterioration, cosmic-ray bit flips, or errors introduced during copying. Unlike a dramatic disk crash, bit rot is insidious: a record may appear intact in a file listing yet open with garbled text, broken images, or missing pages.
For recordkeeping, bit rot directly threatens authenticity and integrity. A record altered by even a few flipped bits may no longer be trustworthy evidence, and the change can go unnoticed until the record is finally needed. Digital preservation programs counter it with fixity checking (storing and periodically re-verifying checksums or cryptographic hashes), redundant geographically separated copies, error-correcting storage, and scheduled migration to fresh media and current formats. These controls echo the integrity and event-tracking expectations in preservation models such as OAIS and PREMIS, ensuring records remain reliable across their full retention period.