In the last few years there's been a lot of discussion about Web 2.0, both about the concept and it's value as a Neologism. My involvement in this is limited, I've read and heard Tim O'Reilly on the topic, and took part in a workshop he organized. There's a lot of confusion out there, however, so I guess it's time for me to make a futile attempt to reduce that confusion. (Since I'm interpreting Tim for much of this, if we disagree on anything you should believe him.)

A lot of the confusion in the Web 2.0 debate is due to people talking about it without really knowing what it is. It was born in 2004:

The concept of "Web 2.0" began with a conference brainstorming session between O'Reilly and MediaLive International. Dale Dougherty, web pioneer and O'Reilly VP, noted that far from having "crashed", the web was more important than ever, with exciting new applications and sites popping up with surprising regularity. What's more, the companies that had survived the collapse seemed to have some things in common.

--Tim O'Reilly

This quote (from the definitional article on Web 2.0) is very revealing. It shows that the term 'web 2.0' refers to a perceived shift going on then (and now) in the nature of the world-wide web. That shift is the essence of the meaning of Web 2.0.

For nonspecialists, ie, ordinary people, "Web 2.0" simply means that something kind of new is happening on the Internet. It involves popular sites like MySpace and YouTube and Flickr and the proliferation of things like blogs. It involves people creating and sharing stuff online. It's a trend, a phenomenon.

--Nicholas Carr

Tim went further than just attaching a name to a trend. Much of his discussion of Web 2.0 has been about trying to understand this trend. In particular he's focused on what are the things that are likely to succeed in this new web world. Much of his definitional article is about this, in particular he lists seven principles of Web 2.0:

• The Web As Platform: Software running as a service over the web (like Google), rather than on a desktop computer (like Netscape).
• Harnessing Collective Intelligence: aggregating information from lots of people rather than a few experts (amazon's community of reviewers, Google's use of links to drive its search algorithms).
• Data is the Next Intel Inside:Owning a specialized database (amazon's database of products, NavTeq's mapping data).
• End of the Software Release Cycle: high frequency of release of new functionality (Flickr deploying new builds up to every half an hour)
• Lightweight Programming Models: simple development environments that are easy for consumers to re-use (Google's simple mapping interface).
• Software Above the Level of a Single Device: lots of devices working together with the web (iTunes and iPods).
• Rich User Experiences: more dynamic user-interfaces closing the gap between web and rich clients.

It's important to realize that these principles are descriptive rather than prescriptive. They are Tim's reflections on what made web sites successful rather than a set of instructions for what makes something Web 2.0. They also form a pretty coherent statement of web 2.0 means. You often run into people who say that Web 2.0 is a meaningless term, but that just makes me wonder if they have read Tim's paper.

I have some sympathy for Nicholas Carr's view that Web 2.0 isn't good jargon because it fails the test that "specialists have to have a shared and clear understanding of what it means." However this lack of a clear understanding is due to the inevitable process of SemanticDiffusion and is neither complete nor unstoppable.

A common misconception I run into is that Web 2.0 is all new stuff. Most of the ideas under Web 2.0 are actually quite old and have been used on the web from early on, for instance Amazon's community or the use of Wikis. The point is that then they were the minority. The Web 2.0 shift is about the principles that were used by a few in the 90's becoming the majority in the future.

All in all I think that the underlying shift referred to by the term Web 2.0 is a significant and real thing. Thus the concept of Web 2.0 is sound. We might argue about whether the term 'Web 2.0' is a good term for this concept - but terms never please everyone and it's stuck so there's little point arguing about it now. The more interesting discussion is over the principles - are they the right set of principles to describe this phenomenon? As part of this we can also talk more concretely about patterns and practices that are in tune with these principles. That's the discussion that Tim wanted to start and that's the one I'm interested in.