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Web 2.0, a phrase coined by O'Reilly Media in 2004,[1] refers to a perceived second-generation of Web-based services—such as social networking sites, wikis, communication tools, and folksonomies—that emphasize online collaboration and sharing among users. O'Reilly Media used the phrase as a title for a series of conferences, and it has since become widely adopted.
Though the term suggests a new version of the Web, it does not refer to an update to Internet or World Wide Web technical standards, but to changes in the ways those standards are used. According to Tim O'Reilly, "Web 2.0 is the business revolution 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."[2].
Some technology experts, notably Tim Berners-Lee, have questioned whether the term is meaningful, since many of the technology components of "Web 2.0" have been present since the creation of the World Wide Web

Web 2.0 is a term describing changing trends in the use of World Wide Web technology
and web design that aim to
enhance creativity, information
sharing, collaboration and functionality of the web. Web2.0 concepts have led to
the development and evolution of web-based communities and hosted services, such as social-networking sites, video sharing
sites, wikis, blogs, and folksonomies. The term became notable after the
first O'Reilly Media
Web 2.0 conference in 2004.[2][3]
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 utilize the Web.
According to Tim
O'Reilly:
Web 2.0 is a term describing changing trends in the use of World Wide Web technology
and web design that aim to
enhance creativity, information
sharing, collaboration and functionality of the web. Web2.0 concepts have led to
the development and evolution of web-based communities and hosted services, such as social-networking sites, video sharing
sites, wikis, blogs, and folksonomies. The term became notable after the
first O'Reilly Media
Web 2.0 conference in 2004.[2][3]
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 utilize the Web.
According to Tim
O'Reilly:


Web 2.0 is a term describing the trend in the use of World Wide Web technology and web design that aims to enhance creativity, information sharing, and, most notably, collaboration among users. These concepts have led to the development and evolution of web-based communities and hosted services, such as social-networking sites, wikis, blogs, and folksonomies. The term became notable after the first O'Reilly Media Web 2.0 conference in 2004.[2] [3] 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 the Web. According to Tim O'Reilly:
| “ | Web 2.0 is the business revolution 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.[4] |
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.[2][3] 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 business revolution 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." [4]
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.[5][6]
In the opening talk of a 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. (This could be seen as a kind of "open source" or possible "Agile" development process, consistent with an end to the traditional software adoption cycle, typified by the so-called "perpetual beta".)
Web 2.0 technology encourages lightweight business models enabled by syndication of content and of service and by ease of picking-up by early adopters.[7]
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 sites:

Web 2.0 websites typically include some of the following features/techniques:
