On September 30, 2005, Tim O'Reillywrote a piece summarizing his view of Web 2.0. The mind-map pictured above (constructed by Markus Angermeier on November 11, 2005) sums up some of the memes of Web 2.0, with example-sites and services attached.
In studying and/or promoting web-technology, the phrase Web 2.0 can refer to a perceived second generation of web-based communities and hosted services — such as social-networking sites, wikis, and folksonomies — which aim to facilitate creativity, collaboration, and sharing between users. The term gained currency following the first O'Reilly Media Web 2.0 conference in 2004. Although the term suggests a new version of the World Wide Web, it does not refer to an update to any technical specifications, but to changes in the ways software developers and end-users use webs. According to Tim O'Reilly,
"Web 2.0 is the businessrevolution in the computer industry caused by the move to the Internet as platform, and an attempt to understand the rules for success on that new platform."
Some technology experts, notably Tim Berners-Lee, have questioned whether one can use the term in a meaningful way, since many of the technology components of "Web 2.0" have existed since the early days of the Web.
An IBM social networking analyst, Dario de Judicibus, has proposed a different definition which is more focused on social interactions and architectural implementation:
"Web 2.0 is a knowledge-oriented environment where human interactions generate content that is published, managed and used through network applications in a service-oriented architecture."
Defining "Web 2.0"
In alluding to the version-numbers that commonly designate software upgrades, the phrase "Web 2.0" hints at an improved form of the World Wide Web. Technologies such as weblogs (blogs), social bookmarking, wikis, podcasts, RSS feeds (and other forms of many-to-many publishing), social software, and web application programming interfaces (APIs) provide enhancements over read-only websites. Stephen Fry (actor, author, and broadcaster), who writes a technology column in the British Guardian newspaper, describes Web 2.0 as
"an idea in people's heads rather than a reality. It’s actually an idea that the reciprocity between the user and the provider is what's emphasized. In other words, genuine interactivity, if you like, simply because people can upload as well as download".
The idea of "Web 2.0" can also relate to a transition of some websites from isolated information silos to interlinked computing platforms that function like locally-available software in the perception of the user. Web 2.0 also includes a social element where users generate and distribute content, often with freedom to share and re-use. This can allegedly result in a rise in the economic value of the web as users can do more online.
Tim O'Reilly regards Web 2.0 as business embracing the web as a platform and using its strengths (global audiences, for example). O'Reilly considers that Eric Schmidt's abridged slogan, don't fight the Internet, encompasses the essence of Web 2.0 — building applications and services around the unique features of the Internet, as opposed to building applications and expecting the Internet to suit as a platform (effectively "fighting the Internet").
In the opening talk of the first Web 2.0 conference, O'Reilly and John Battelle summarized what they saw as the themes of Web 2.0. They argued that the web had become a platform, with software above the level of a single device, leveraging the power of the "Long Tail", and with data as a driving force. According to O'Reilly and Battelle, an architecture of participation where users can contribute website content creates network effects. Web 2.0 technologies tend to foster innovation in the assembly of systems and sites composed by pulling together features from distributed, independent developers (a kind of "open source" development and an end to the software-adoption cycle (the so-called "perpetual beta"). Web 2.0 technology allegedly encourages lightweight business modelsenabled by syndication of content and of service and by ease of picking-up by early adopters.
Tim O'Reilly provided examples of companies or products that embody these principles in his description of his four levels in the hierarchy of Web 2.0-ness. Level-3 applications, the most "Web 2.0"-oriented, only exist on the Internet, deriving their effectiveness from the inter-human connections and from the network effects that Web 2.0 makes possible, and growing in effectiveness in proportion as people make more use of them. O'Reilly gave as examples eBay, Craigslist, Wikipedia, del.icio.us, Skype, dodgeball and AdSense. Level-2 applications can operate offline but gain advantages from going online. O'Reilly cited Flickr, which benefits from its shared photo-database and from its community-generated tag database. Level-1 applications operate offline but gain features online. O'Reilly pointed to Writely (now Google Docs & Spreadsheets) and iTunes (because of its music-store portion). Level-0 applications work as well offline as online. O'Reilly gave the examples of MapQuest, Yahoo! Local and Google Maps (mapping-applications using contributions from users to advantage can rank as "level 2"). Non-web applications like email, instant-messaging clients and the telephone fall outside the above hierarchy.
Some authors understand 2.0 as
"all those Internet utilities and services sustained in a data base which can be modified by users whether in its content (adding, changing or deleting- information or associating metadates with the existing information), or how to display them, or in content and external aspect simultaneously." (Ribes, 2007)