UPDATE: Tim O'Reilly has since offered the following compact definition, that captures fairly well the essence of what people are referring to as Web 2.0:

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.

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Thomas Burg posts a neat little what is Web 2.0 roundup that draws encouragement from a BBC piece suggesting that many people consult blogs when shopping:

"Respondents said they trusted blogs because they were written by real people and based on actual experiences."

Interesting stuff. The phrase Web 2.0 is bubblicious right now, with both Business Week and the Economist dedicating some intelligent coverage to its various manifestations in recent weeks. Elsewhere, I notice 198 occurrences of the term in my RSS news reader, which means that lots of people are talking about it.

Like any self-respecting buzzword, Web 2.0 has its own conference and streams at several others. It is available as a My *.* version, and has spawned a semantic bunfight among early adopters (see also Sam Ruby on this one), with some people suggesting we are already on Web 3.0. It has also been crowned by the now traditional act of danah boyd rejecting all preceding business and technology buzzwords in favour of equally vapid social science jargon (Web 2.0 as a process of glocalization).

Web 2.0, il est arrivée !! Mais ... qu'est-ce que c'est?

I gave one of my introduction to Social Software talks (PDF presentation) the other week at a well-attended British Computer Society meeting, and I fell back on the rather sub-optimal wikipedia definition as a starting point, but demonstrated the value of Web 2.0 through the tools it has spawned and the use cases they support.

Ross Mayfield suggests the rather sweet formulation: Web 2.0 is Made of People!, which is true on several levels and hard to disagree with. Peter Merholz, though, has noticed that for some people the opposite is the case, in the sense that Web 2.0 for techies is about machine readable content and protocols, whilst for designers it is about experience.

Elearningpost reports John Hagel's attempted synthesis of the two angles, saying that Web 2.0 is "an emerging network-centric platform to support distributed, collaborative and cumulative creation by its users," or as somebody else put it:

"Web 2.0 = Tim Berners Lee's Semantic Web meets social software"

Dave Pollard mentions some of the elements of this network-centric platform in a series of posts about the Connect and Collaborate Conference. A good indicator of the spread of this network-centric vision is the number of open APIs that are now available to manage the flow of content and ideas between different systems. Also, the Web 2.0 meme map that emerged from a brainstorm at O'Reilly's foo camp does a good job of pulling together these various strands and identifying linkages.

Among the larger web companies, Yahoo (inc. Flickr) and Google are both well placed to exploit this phenomenon. Google's various new services have been discussed at length, but Yahoo's entrant into this space - My Web 2.0 - is very interesting too. Ross Mayfield had some useful insights into their strategy when it was made public:

Yahoo views the web as a play with three acts.

Act I: Public (e.g. Web Search)
Act II: Personal (e.g. Desktop Search)
Act II Social (e.g. search communities)

People we work with at Yahoo Europe are very excited about this emphasis on Web 2.0 ideas and see it playing an even greater role in their marketing and product development in the future.

But how new is new?

Much as I hate these techie buzzwords, we are indeed lacking a coherent description of the various tools, techniques and services that are coming together to fulfil (for the first time) the exciting potential of the interweb that got us all so motivated in the mid-nineties. For that reason alone, I have noticed that the phrase "Web 2.0" has crept into our conversations over recent weeks as a shorthand for all the exciting stuff that is going on. Like 'wiki', 'Web 2.0' is a silly name for something really useful and important, and I just hope that it doesn't act as a further barrier between us and the ordinary users whose participation we need to create the network effects we crave.

The good thing, though, is that so many interesting people with so many fantastic ideas are having these conversations, and we are meeting them in the most unlikely places. Truly incredible and also slightly humbling.

Another recurring theme in these conversations is the extent to which much of what we are doing in Web 2.0 is not in the least bit new. Once client in Amsterdam told me last week how he was doing decision support systems on old Apple Macs in the 1980's; somebody I helped run a wiki at a seminar a few days ago had been using real-time in-meeting systems (also on Macs) before wikis were invented; somebody at the BCS meeting I mentioned above suggested that RDF owes much to the older generation of programming languages, and somebody else reminded us that AI researchers had been tackling ontology development and semantic inference for many, many years before the semantic web.

So, Web 2.0 may sound shiny and fresh, but it is actually made up of old elements that we are using in innovative new ways. For me that's part of the value proposition. I don't mind going back to the idea of home pages, chat and keyword classification every ten years if necessary, as long as we improve our use of the basic technologies with every iteration.