Integrity Check

Definitions

A verification that data has not been altered between one point and another, whether by corruption or by deliberate tampering. The distinction between those two threats determines the right mechanism. Checksums such as CRC32 detect accidental corruption cheaply but are trivially forged, so they say nothing about tampering. Cryptographic hashes such as SHA-256 make forgery computationally infeasible, but an attacker who can change the data can usually change the published hash alongside it. Only a keyed construction such as an HMAC, or a digital signature, establishes both integrity and authenticity, which is why package managers sign their indexes rather than merely hashing them. The recurring practical failure is publishing a hash over the same channel as the file it protects, which secures nothing against an attacker holding that channel.
In plain English: A check to confirm something has not been changed or corrupted.
Example: "The startup sequence failed the integrity check because the bootloader image had been modified."