[common] Also bit decay. 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.
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-detecting circuitry to compensate for them). The notion long favored
among hackers that cosmic rays are among the causes of such events turns
out to be a myth; see the cosmic rays entry for
details.
The term software rot is almost synonymous.
Software rot is the effect, bit rot the notional cause.
