Jennifer Zaino
SemanticWeb.com Contributor

A group of semantic web startups -- and one established search vendor -- is behind a new semantic tagging format for web pages. Common Tag is described as an open tagging format for creating references to unique, well-defined concepts, complete with metadata and their own URLs, and its development was supported by AdaptiveBlue, DERI (NUI Galway), Faviki, Freebase, Yahoo!, Zemanta, and Zigtag.

Common Tag is based on RDFa, which describes how to interleave data inside HTML, but not which data in which way, according to Zemanta CTO Andraz Tori.

"Common Tag does that -- it prescribes how semantic (exact) tags can be embedded, so different services can understand that they are tags and what's behind them," Tori stated.

The basic idea, he explains in an email interview, is to help people and organizations that are publishing content make it easy to enhance their offerings. Enabling cross promotion of content and a better user experience while searching and browsing increases the value of content. As an example, he references a movie review site that could automatically generate sidebars that pull movie details from Freebase, and even add ticket-purchasing capabilities.

"AdaptiveBlue's Glue browser extension will know that that movie review site and Wikipedia page of the movie both talk about the same subject and allow users to move between them and connect fans of that specific movie from both sites," he states.

Common Tag was born in informal discussion with Yahoo researcher Peter Mika about what would be the easiest way to let publishers get more out of their content by semantically marking it up, Tori notes. "We've seen Common Tag as a vehicle to make Web content more discoverable, connected, and engaging," Tori said. "We ... learned [from] previous efforts and decided that we need a full blown ecosystem from day one. Not just academic support, but web industry support. As you can see the idea was well received."

What's the benefit to the companies behind Common Tag? Tori notes that they are active in different parts of the content creation and consumption circle, from authoring and bookmarking to providing data, searching and browsing.

"As more publishers and consumers enter the world where machines can understand the content and meaningfully help users, we will see bigger demand for [the] services our companies are offering," he says. As examples, "while Glue provides better experience to users on sites that have connected data, Glue itself gains more sites that their tools can enhance. As more publishers decide to tag their content, Zemanta is able to offer them help with auto-tagging."

Tori is encouraged by the idea's reception among industry players. "While I don't have a crystal ball I have a good feeling on [the] initial responses that we got," he says. "This is the first time that this number of web companies have stepped together from day one to introduce a tagging standard. We tried to build on previous academic efforts. Over that we added business incentives to participate. Hopefully we solved the chicken and egg problem!"