PS3:MD5 Hash
The MD5 hash, also known as the checksum for a file, is a 128-bit value that is a nearly-unique fingerprint of a file. By checking the hash of a file against the value posted on the download page, you can ensure that you have the correct file, and that it has not gotten corrupted along the way. You can either use a website to check the the MD5 hash, or use an installed program to check it. You can find a list of common firmware's MD5 values on the firmwares page or plug the MD5 in on this site to see what firmware it corresponds to.
Method 1 - Website
Certain websites, such as MD5File.com, will allow you to upload a file to generate a MD5 hash to check against your known MD5 hash. Simply make sure that the MD5 box is selected, drag your file onto the webpage, and compare the resulting MD5 hash with your known MD5 hash. If they match, your file is identical to the original.
- Note the popular site "OnlineMD5" seems to give wrong hashes for some files.
Method 2 - Program
You can install programs, such as HashTab, which will generate different checksum hashes for a file. In the case of HashTab, you can right-click any file, select Properties, and it will have an integrated information tab that shows all the major hash values. Simply click the MD5 line and paste your known MD5 hash into the text field. If they match, your file is identical to the original.