Note: The one that everybody’s been waiting to kill. This definition is taken from Tim O’Reilly’s blog, who was at least there when the phrase was coined. Boy, he’s going to love this.
Web 2.0 is the network as platform, spanning all connected devices; Web 2.0 applications are those that make the most of the intrinsic advantages of that platform: delivering software as a continually-updated service that gets better the more people use it, consuming and remixing data from multiple sources, including individual users, while providing their own data and services in a form that allows remixing by others, creating network effects through an “architecture of participation,” and going beyond the page metaphor of Web 1.0 to deliver rich user experiences.
(from the man himself, Tim O’Reilly)