Here are some Web 2.0 definitions. In common seem to be the idea of a platform or platforms which mobilize collective co-creation capacity, and support on-demand availability of recombinable data and services.
O’Reilly Radar > Web 2.0: Compact Definition?]
So, in the spirit of entering the conversation, let me suggest that Web 2.0 ultimately refers to “an emerging network-centric platform to support distributed, collaborative and cumulative creation by its users.” [Edge Perspectives with John Hagel: What is Web 2.0?]
He goes on to examine each of these attributes in turn. Richard MacManus includes the following in a longer discussion:
Web 2.0 at its most basic is using services on the Web. Some examples: Gmail for email, Flickr for photo-management, RSS for news delivery, eBay for shopping, Amazon for buying books. That’s why the Web is being called a platform – because all of these services are being built and used on the Web. Why Web 2.0 only now though – hasn’t Amazon been around since 1995? Why yes, but it’s taken until 2005 for broadband and web technology to catch up and reach a ‘tipping point’ – the Web is fast becoming the platform of choice for developers, business, media, public services, and so on. [Read/Write Web]