A cyclic redundancy check (CRC) is a method used to detect errors in digital data. It works by applying a mathematical algorithm to a block of data, generating a short, fixed-size binary value called a checksum. This checksum is then sent along with the data. When the data is received, the same algorithm is applied to check if the checksum matches, indicating whether the data is intact or has been corrupted. CRCs are commonly used in various applications, including network communications, data storage, and file formats. They help ensure data integrity by identifying errors that may occur during transmission or storage, making them essential for reliable data handling.