A given hash uniquely represents a file, or any arbitrary collection of data. At least in theory. This is a 128-bit MD5 hash you're looking at above, so it can represent at most 2128 unique items, or 340 trillion trillion trillion. In reality the usable space is substantially less; you can start seeing significant collisions once you've filled half the space, but half of an impossibly large number is still impossibly large.Back in 2005, I wondered about the difference between a checksum and a hash. You can think of a checksum as a person's full name: Eubediah Q. Horsefeathers. It's a shortcut ...