The term used to refer to this “new phase” of the Internet is Web 2.0 . Although this term is heavily abused and applied to anything new on the web, “Web 2.0” had a specific meaning for the person who invented it, book publisher Tim O'Reilly. In “What is Web 2.0,” the original article he wrote in 2005 introducing the idea, he highlights seven features a Web 2.0 site must have. You can read the original article here:

      http://www.oreillynet.com/pub/a/oreilly/tim/news/2005/09/30/what-is-web-20.html?page=1