Cyclic Redundancy Check (CRC) is a special hash function used to detect errors during data transmission or storage. Due to its simplicity and good mathematical properties this is a very common way of realizing the checksum. The checksum is usually sent or stored along with data that could be transmitted or stored in error. After receiving the data it is recalculated independently. If the independently calculated checksum is different from the transmitted or stored one it is clear that an error occurred during transmission or storage. If it is the same then almost certainly no error occurred.


Source: Wikipedia