The most common case: any situation in which only one character in a file is different. For one in every 128 pairs of these files, more or less, fc.exe will sa

The most common case: any situation in which only one character in a file is different. For one in every 128 pairs of these files, more or less, fc.exe will say "no differences found". Are you asking why anyone would ever change only one character in a file? Typo corrections come to mind, or mild file corruption. I recovered a ton of files from a failing drive a few years ago, and quite a few of the text files had just a character or two corrupted. I'm not sure what people generally use fc for -- I don't -- so it's hard to say how serious the impact might be when it fails.