bit rot

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bit rot

A hypothetical disease the existence of which has been deduced from the observation that unused programs or features will often stop working after sufficient time has passed, even if "nothing has changed". The theory explains that bits decay as if they were radioactive. As time passes, the contents of a file or the code in a program will become increasingly garbled.

People with a physics background tend to prefer the variant "bit decay" for the analogy with particle decay.

There actually are physical processes that produce such effects (alpha particles generated by trace radionuclides in ceramic chip packages, for example, can change the contents of a computer memory unpredictably, and various kinds of subtle media failures can corrupt files in mass storage), but they are quite rare (and computers are built with error detection circuitry to compensate for them). The notion long favoured among hackers that cosmic rays are among the causes of such events turns out to be a myth.

Bit rot is the notional cause of software rot.

See also computron, quantum bogodynamics.
This article is provided by FOLDOC - Free Online Dictionary of Computing (

bit rot

Bit rot, also called "format rot," is the inability to access digital data because hardware and software do not exist to read the format. For example, files saved on tape cartridges might not be retrievable because the drives are not available. Although computers no longer come with a built-in floppy disk drive, floppies are still readable because an external drive can be plugged into a PC via USB.

The Solution to Digital File Rot
One way to prevent archival bit rot is to be aware of format changes. Whenever a file format is updated, the application that reads it will also be changed. Within a few years of such an occurrence, users should open important documents and save them in the new format. For example, the original .DOC file format created by Microsoft Word in the 1980s became a legacy format after the new .DOCX format debuted in 2007. Because billions of .DOC files exist in the world, Microsoft has continued to support the old format in subsequent versions of Word, at least for now. However, lesser-known applications may not have such extended support. See data fade and software rot.
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