Systems That Get Better the More People Use Them

In Publishing 2.0, Tim O'Reilly says Web 2.0 is 'any network effect that makes a system better the more people use it.' Web 2.0 isn’t just user-generated content; it’s harnessing the collective intelligence of your users to make your system better.

Johnson, Tom H. I'd Rather Be Writing (2008). Articles>Documentation>Web Design>Social Networking