Main use of hashing is to compare to files for equality. Without opening two document files to compare them word-for-word ,the calculated hash values of these files will allow the owner to know immediately if they are different.
Hashing is also used to verify the integrity of a file after it has been transferred from one place to another , typically in a file backup program like SyncBack.To ensure the transferred file is not corrupted , a user can compare the hash value of both files. If they are the same, then the transferred file is an identical copy.
In some situations , an encrypted file may be designed to never change the file size nor the last modification date and time (for example , virtual drive container files).In such cases it would be impossible to tell at a glance if two similar files are different or not ,but the hash values would easily tell these files apart if they are different.
