Got a few choice thoughts about what you see on the Web? Enter Annotea, a new technology that lets you annotate existing Web documents with commentary of your own.

Annotea is an open-source initiative sponsored by the non-profit World Wide Web Consortium (W3C), the closest thing the Internet has to a governing body. Built into W3C’s Amaya browser, Annotea allows third parties to append information to existing Web pages. The annotations are stored on a separate server, invisible to the viewer unless Annotea is activated.

So exactly what kinds of annotations are we talking about? “Comments, notes, explanations or other types of external remarks that can be attached to any Web document or a selected part of the document without actually needing to touch the document,” describes the W3C Web site.

The idea, says W3C communications director Janet Daly, is simple: “being able to annotate a document in a useful way.”

Annotea’s concept itself is not new. A commercial application called Third Voice attracted attention two years ago with a similar but proprietary technology. With no clear revenue plan, Third Voice became yet another dot-com casualty in April.

The W3C hopes that by pushing the technology as an open-source solution, Annotea will take root as a useful “metadata” application–a way to provide information about online information online.

Building a Meta World

Annotea is part of the W3C’s Semantic Web project, which aims to overhaul the basic language of the Web to make categorizing and describing online information faster and easier.

Consider how you locate information in a traditional library: using either a computer database or good old card catalog, you can sort by author, title, subject, publisher, date and other criteria. Librarians and archivists have long employed this type of metadata system for good reason-it’s simple and efficient.

The W3C hopes to build this concept of metadata into the very core of the Web by way of its Resource Description Framework. RDF itself is built on XML, a universal format for structured documents and data on the Web. And Annotea is built around RDF.

“RDF is a metadata standard that allows individuals to create information about information that they find on the Web,” says Daly.

By way of RDF, data online can be tagged and sorted in the same fashion as within library databases or proprietary online services such as Lexis-Nexus. “RDF allows you to make what are called assertions about documents,” Daly says. “That could be an author’s name, a title or a publisher. RDF provides a technical basis for describing those assertions, so machines can understand what you’re saying about a document.”

Who Do You Trust?

With Annotea, users can get analyses and commentaries that go beyond a library computer search. It provides a tool for third parties to ascribe value to Web content.

“If you have metadata that provides information about the sources, the author, or other analyses or evaluations, then you’re in a better position to make an informed decision,” says Daly.

An immediate problem is apparent: how can you trust an author or third party to give a fair analysis of an article? In other words, who gives authority to metadata evaluations?

“It could be from anywhere,” Daly says. “You could say, ‘Based on my own knowledge and value base, there are certain evaluations I trust more than others.’ In the same way you make your judgments about media now-what magazines you trust, what financial services provider you choose.”

Daly is quick to note that the Semantic Web vision is still in its early development stages. But by providing open source tools like XML and RDF, the W3C hopes to pave the way.

“It’s only been 11 years since the first successful implementation of the Web, when a browser first communicated with a server and got an answer,” she points out. “The adoption of the Semantic Web is really in its infancy.”