What is Checksum?

One of the ways in which Checksum is used is as a means of verifying that a file is complete, uncorrupted and matches the original file. It is especially useful for checking large software downloads like the ISO file for an operating system. The vendor of the ISO will normally provide a set of of hash values which can be used to verify the integrity of the ISO download.

For an example of how to perform a SHA256 Checksum in Windows see Checksum in Windows.