No longer in a proper state (or, as a verb, to cause to be no longer in a proper state). The term is most commonly used in connection with data that is being stored or transmitted: corrupt data when recovered or received has been altered from the version that was originally stored or transmitted. Since corrupt data may either be of little use, or may be positively harmful if used, most systems that store or transmit data include mechanisms to detect the presence of corruption, and to allow the original data to be recovered.