If you are getting the Checksum error when trying to extract a RAR archive file using WinRAR, see this post and fix the error.

Monkey's Audio and checksum errors... how to fix? shannim Sep 30, 2002 Jump to latest Follow Reply ...

A checksum is a string of characters which uniquely identifies afile, a digital fingerprint. Change even a few bytes of a file–forexample, by infecting it with a virus or replacing an old ...

PS Hash calculates checksum & hashes of files The idea behind it is to calculate file hashes and checksums and then compare their contents using a specialized algorithm.

And, the slightest change to the file's contents even by a character or pixel will drastically change its checksum. You can try this in practice by recalculating the checksum of your altered file.