Bit rot

Bit rot is a colloquial computing term used to facetiously describe the spontaneous degradation of a software program over time. The term implies that software can literally wear out or rust like a physical tool. Bit rot is also used to describe the discredited idea that a computer's memory may ocassionaly be altered by cosmic rays.

When a program that has been running correctly for an extended time suddenly malfunctions for no apparent reason, programmers often jokingly attribute the failure to bit rot. Such an effect may be due to a memory leak or other nonobvious software bug. Many times, although there is no obvious change in the program's operating environment, a subtle difference has occured that is triggering a latent software error.

Attributing a program error to bit rot is comparable to placing blame for a plane crash on a gremlin.