A simple picture of Web evolution
05.11.2007
The traditional World Wide Web, also known as Web 1.0, is a Read-or-Write Web. In particular, authors of web pages write down what they want to share and then publish it online. Web readers can watch these web pages and subjectively comprehend the meanings. Unless writers willingly release their contact information in their authored web pages, the link between writers and readers is generally disconnected on Web 1.0. By leaving public contact information, however, writers have to disclose their private identities (such as emails, phone numbers, or mailing addresses). In short, Web 1.0 connects people to a public, shared environment — World Wide Web. But Web 1.0 essential does not facilitate direct communication between web readers and writers.
The second stage of web evolution is Web 2.0. Though its definition is still vague, Web 2.0 is a Read/Write Web. At Web 2.0, not only writers but also readers can both read and write to a same web space. This advance allows establishing friendly social communication among web users without obligated disclosure of private identities. Hence it significantly increases the participating interest of web users. Normal web readers (not necessarily being a standard web author simultaneously) then have a handy way of telling their viewpoints without the need of disclosing who they are. The link between web readers and writers becomes generally connected, though many of the specific connections are still anonymous. Whether there is default direction communication between web readers and writers is a fundamental distinction between Web 1.0 and Web 2.0. In short, Web 2.0 not only connects individual users to the Web, but also connects these individual uses together. It fixes the previous disconnection between web readers and writers.
source: ZDNet