"Web 2.0" refers to a perceived second generation of web development and design, that facilitates communication, secure information sharing, interoperability, and collaboration on the World Wide Web.
Web 2.0 concepts have led to the development and evolution of web-based communities, hosted services, and applications; such as social-networking sites, video-sharing sites, wikis, blogs, and folksonomies.

The term was first used by Dale Dougherty and Craig Cline and shortly after became notable after the 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 rather to changes in the ways software developers and end-users utilize 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 a platform, and an attempt to understand the rules for success on that new platform.


Related articles :

• http://www.oreillynet.com/pub/a/oreilly/tim/news/2005/09/30/what-is-web-20.html
• http://blogs.zdnet.com/web2explorer/?p=5
• http://www.techsoup.org/learningcenter/webbuilding/archives/page9344.cfm
• http://www.go2web20.net/