How to check if downloaded file is correct using sha256 hash

When we download a file from the Internet, we have to verify that the correct file has been downloaded: someone could have changed the file for another or some errors could occur when transferring the file. We can verify that the file is correct using a hash algorithm. In this video, the hash SHA256 algorithm is used (md5 is deprecated!).
I have used a debian file as an example, but the process can be used with any other file: the only requirement is to have the hash SHA256 code of the original file to be able to compare it with the hash SHA256 code for the downloaded file. To calculate the hashing SHA256 code for the file, an online web page has been used, although there are desktop tools available to not depend on a third party.