Why file integrity swindles after numerous transfers between storage mediums

[The invoker]

Alright, so it's not really thread-worthy, but I've had some certain files for a long amount of time--about 3 or so years--and some of them have corrupted in one way or another. Say for instance, I have certain pictures, parts of the picture is just full out grey and the other part is what's left of the picture. Other examples are that I had an mp4 or avi that was from a while back, but now depending on what media player you use, it either says "cannot render this file" or "cannot play this file". But like I said, I've had these files for quite some time and have been trying to keep them safe, so normally, I've copied them to other hard drives but now I have a computer that can hold all of the files, some of them I can't even get information from. I'm just curious as to why this happens.

 

[Phillip Corcoran]

All hard drives start to fail eventually - - data disappears gradually and/or file corruption occurs (the latter can also be caused by bad RAM).

That's why it's wise to have multiple backups.

 

[The invoker]

All hard drives start to fail eventually - - data disappears gradually and/or file corruption occurs (the latter can also be caused by bad RAM).

That's why it's wise to have multiple backups.

I do agree that it's wise to have multiple backups, that's why I tried. I tried copying the same files (let's call them "Movie 1" and "Movie 2" ) on to multiple hard drives to assure that I could keep the files for longer periods of time. i.e copying Movies 1 and 2 on to HDD A alongside copying it also to HDD B and HDD C. Even after I copy them over to other HDDs, after a time, it becomes corrupted.