A cyclic redundancy check (CRC) is an error-detecting code designed to detect accidental changes to raw computer data, and is commonly used in digital networks and storage devices such as hard disk drives. Blocks of data entering these systems get a short check value attached, derived from the remainder of a polynomial division of their contents on retrieval the calculation is repeated, and corrective action can be taken against presumed data corruption if the check values do not match.-A cyclic redundancy check (CRC) is an error-detecting code designed to detect accidental changes to raw computer data, and is commonly used in digital networks and storage devices such as hard disk drives. Blocks of data entering these systems get a short check value attached, derived from the remainder of a polynomial division of their contents　on retrieval the calculation is repeated, and corrective action can be taken against presumed data corruption if the check values do not match.