When you save something on your computer, it's saved somewhere, but not necessarily preserved and organized. You don't necessarily ensure the information will be transferred when the next version of the software appears. If, for example, you go back to your old computer, which is in your basement, you may find files that you won't even be able to open. You've saved them, but they haven't been preserved. That means they aren't in a trusted digital repository that guarantees you'll be able to read them in 10 or 20 years. That's our challenge, and it's an enormous one.
On May 4th, 2010. See this statement in context.