When you have access to more than one computer, you might starting copying your files around, badly evolving each copy of your precious folder as time passes. One day, you realize that one or more computers have developed faults that introduced a few single-bit errors in files. (like a defective drive controller or maybe the results of some malware infection)

So you have 3 (or more!) copies of a file and you're not sure which one is the pristine version. Luckily, the single-bit errors appear to be randomly-distributed and thus if there are 3 or more copies of the same file with different errors, then it should be possible to fix the errors by doing a bit-by-bit simultaneous scan of all the copies and resolving bits that differ by a vote.

You can probably do this manually with 3 copies of one file that contain varying single-bit errors. When you have upwards of 5000 of those corrupted files, you write a program like I did. :)