and about paper
almost forgot: The problem with relying on paper to back up your digital data is capacity. You know how they use those loopy analogies about memory capacity like "eqivalent to all the books in the Library of Congress"? Actually using paper as a backup will make all those analogies horrifyingly concrete. Considering how many petabytes we generate every day, paper backup would bury the surface of the Earth a mile deep in cellulose.