Many users shy away as soon as they hear the words hash or shell extension because of the connotation that the conversation will turn into a highly technical - and geeky - one. The concept itself however is pretty simple that even a inexperienced computer user should understand it.
A hash is just a string that [...]

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MD5 (Message-Digest algorithm 5) can be used as a way of checking that a computer file has not been maliciously or accidentally altered. To put it simple, it works like a fingerprint. So, nowadays most of websites includes this information to their software, which looks like this:

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