What Is An MD5 Checksum On File Downloads?

On many download sites, you may see an MD5 checksum (or hash) included on the page next to the file download link. If you have ever wondered what this is and how it is useful, then hopefully this tip will help.

An MD5 checksum (you can read the full info on Wikipedia here) is basically a string of letters and numbers determined by the characteristics of a particular file. By making a small change to the file, a completely new MD5 hash string would be generated.

This becomes useful when you download a file because you can compare the MD5 checksum of the file you downloaded against what the download site says it should be in order to ensure the file is the same. If the MD5 result between the two files are different, then the file you have has been tampered with. For a good demo of MD5 and how you can use it, check out this YouTube video.

While MD5 is not 100% foolproof (nothing is), it is a very good way to make sure you are getting what you think without and “surprises”.

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Stacey
If the MD5 does not match, it also could be a indicator of a bad download. When I am trying the newest flavor of Ubuntu, I always do the MD5 check as it’s a huge file size and the least little download hic-cup can cause massive issues on installation. If the MD5′s match, I know that any install issues go further than a bad download.
http://www.Scopulus.co.uk Scopulus
Excellent download from the youtube above.
http://none David M
I see GPS checksum errors pop up occasionally on my chart software. The satellites send files as well, mostly almanacs that tell the GPS in advance what satellites it should be “hearing” and when.