For those who don't follow it all the time, it might even be hard to remember what all the pieces of Web 2.0 are (and keep in mind, these elements are often reinforcing, so Web 2.0 is definitely not a random grab bag of concepts). Even compact definitions are sometimes a little hard to stomach or conceptualize But the one I like the best so far is Michael Platt's recent interpretation just before SPARK. Keep in mind, the shortest definition that works for me is that "Web 2.0 is made of people." However, it's so short that important details are missing and so here's a paraphrase of Platt's summary.

Key Aspects of Web 2.0:

- The Web and all its connected devices as one global platform of reusable services and data
- Data consumption and remixing from all sources, particularly user generated data
- Continuous and seamless update of software and data, often very rapidly
- Rich and interactive user interfaces
- Architecture of participation that encourages user contribution

I also wrote a review of the year's best Web 2.0 explanations a while back and it goes into these elements in more detail if you want it. But there's a lot more to Web 2.0 than these high level elements would indicate. A key aspect not mentioned here, though I cover it in Sixteen Ways to Think in Web 2.0, is the importance of user ownership of data. The centrality of the user as both a source of mass attention (over a hundred million people, probably 2 or 3 times that many, are online right now) and an irreplaceable source of highly valuable data, generally encourages that the user be handed control of the data they generate. If control over their own attention data is denied them, they will just go to those who will give them that control. This gives some insight into the implications of Web 2.0 concepts, which were mostly gathered by examining prevailing trends on the Web. Forrester is calling the resulting fall out of these changes Social Computing and it'll be interesting to see what the effects of the widepsread democratization of content and control will ultimately be a generation from now.

"Web 2.0 is comprised of applications that use sophisticated user interfaces, that use the Internet as an operating system, that connect people, and that encourage collaboration."

On April 1st, 2004, Google launched GMail, which went on to ignite the whole Web 2.0 / AJAX revolution which we are witnessing right now. There is no agreed definition of Web 2.0. I like to think of it as the re-birth or second-coming of the web. The Web 2.0 websites are more like web applications, and have a rich, highly interactive and generally well designed user interface. They could also be using web services offered by other sites (for eg, Google Maps, Flickr photo web service, etc). Syndication and community are also associated with a site being Web 2.0. AJAX is the technical term which is responsible for the increased interactiveness of Web 2.0 websites. But the fundamentals remain the same - what's under the hood of a Web 2.0 application is as important as it was a few years ago.