A mistake of any kind.
In computing, a discrepency between a predetermined correct value or behavior and the actual observed value or behavior. Errors in computing can be fairly trivial (such as an attempt to write data to a disk drive that contains no disk) and will provoke a gentle (if occasionally cryptic) rebuke from the computer (an error message). A particular action may also result in a fatal error, which can render the system inoperative and/or cause it to crash.