What technique is used to check if data has been lost or written over during transfer?

The technique used to check if data has been lost or written over during transfer is known as a checksum. A checksum involves calculating a value based on the contents of the data, which is then sent along with the data during transfer. When the data is received, the checksum is recalculated, and if it matches the original checksum, it indicates that the data has been transferred accurately without loss or corruption.

Checksums are particularly effective for error detection, allowing systems or users to verify the integrity of data after transmission. If discrepancies are found, it suggests that data has either been lost or altered, prompting necessary corrective actions.

While parity assists in verifying the integrity of a single bit in data transmission, it is less comprehensive than checksums for datasets as it does not provide a means to detect errors in larger blocks of data. Moreover, compression and encryption serve different purposes, primarily focusing on reducing data size and securing data, respectively, rather than verifying integrity post-transfer.