A checksum is a value used to verify the integrity of data that has been transmitted or stored. It is calculated by applying a mathematical function to the data, and the result is appended to the data. When the data is received or retrieved, the checksum is recalculated and compared to the appended value. If the two values match, it is likely that the data has not been corrupted in transit.
There are many different checksum algorithms, and each one has its own advantages and disadvantages. One of the most common checksum algorithms is the ISO 3309 cyclic redundancy check (CRC). The CRC algorithm is used in a wide variety of applications, including data storage, data transmission, and software development.