Computers don't handle visual imagery with the same native ease with which they parse text or crunch numbers. Flickr was the first site to solve this problem with something called collaborative tagging. The idea is that if everyone is allowed to tag everyone else's uploaded photos, then a rough-and-ready categorization will naturally emerge from the wisdom of the crowd. It works because it has to — there aren't enough librarians in the world to look after Flickr's archive of 3 billion photos, much less file them away for future reference. But it also works because the many really is smarter than the sum of its parts. The Library of Congress has even started to poll the Flickr hive mind when cataloging its own photos.