PAR & PAR2 Files
Explained in Plain English

PAR files contain error-correction data that can be used to fix files that become corrupted during the upload/download process. PAR files can be used to protect any kind of file. For example, suppose you send a video file to your mom, but she can't play it because it is damaged. Instead of re-sending the whole file, you could send her a much smaller PAR file to fix it. And the next time you send her a video file, you could send a PAR file at the same time. That way, if the video file is damaged, she could fix it with the PAR immediately.

PAR files don't have a separate life of their own. You don't decompress them like you do RAR files. PAR's only exist to fix other files. Sometimes in a newsgroup you will see a set of PAR's posted with no other files. The poster did that as a favor to somebody who needed to fix a file that he had downloaded previously. So, you don't need to download PAR files unless you need them to fix a damaged file in your possession. Of course, it is not always obvious if a file is damaged. For example, there could be small flaws in a video that you can't find unless you watch the whole thing very closely. It is not a bad idea to download the PAR's to make sure that your files are OK.

PAR files are able to magically fix, and even re-create missing files. Suppose you download 9 of the 10 RAR's from a binary newsgroup that contain a video file, and you can't find the 10th. If the poster included some PAR files, you can download them and actually re-create the missing file! If the poster did not include any PAR's, as newbie posters often do, you could post a message in the group and ask somebody who was able to get all the files to make, and post some PAR's for you. Anybody can make PAR's as long as they have a good copy of the files in question.

There are two generations of PAR technology in use: PAR and PAR2. PAR filenames look like this:

somefile.p01
somefile.p02
somefile.p03

PAR2 filenames look like this:

To use PAR files, open the first PAR or PAR2 with the free PAR decoder in SuperNZB. SuperNZB will use the PAR's to examine the target files (RAR's, AVI's, etc.) and fix them if needed.

Both PAR and PAR2 do the same thing, but PAR2 is much better. Look at the PAR2 filenames above. The '+01', '+02', and '+05' indicate how many 'blocks' each file has, and that can save you download time. To do that, you would first download the associated files whether they are RAR's, AVI's, etc. Then you would download the file that ends with '.par2.' Run that file through your un-PARing program, and it will tell you how many more blocks you need, if any. If you needed seven blocks, then you could download the second and third PAR files. If you only needed two blocks, then you could just download the second file.

PAR files cannot contain viruses, so there is no risk in using them.