Check out this video on Web 2.0. It really had simplified the meaning of Web 2.0. By the way the creator of this video was highlighted as 2007 Rave Award winner by Wired magazine, which wrote:
"How do you sum up the power and potential of Web 2.0 in a 271-second video? By moving really, really fast. When Michael Wesch, who teaches cultural anthropology at Kansas State University, made “Web 2.0… The Machine Is Us/ing Us,” he’d been working for months on an academic paper that would explain new Web tools. As he struggled to define concepts like hypertext, tagging, mashups, and wikis, he had an epiphany: He was working in the wrong medium. He needed to use the tools of Web 2.0 to explain Web 2.0. Anthropology — humans studying the experience of being human — is a recursive discipline, and Wesch’s is a recursive video, cutting quickly between screenshots that show him bookmarking Web sites with del.icio.us, creating a blog with Blogger, and posting pictures on Flickr."
Enjoy the video.