Having already indexed most of the information on the Internet, tech giant Google Inc. has begun testing a new Web service known as Knol, which may in time grow to challenge the online encyclopedia.

According to a post on the Official Google Blog, the new tool encourages experts to write articles — called knols, which stands for unit of knowledge. Topics would be in an expert's field of interest, and knols would be hosted by Google and included in the results lists generated by the company's search engine.

“A knol on a particular topic is meant to be the first thing someone who searches for this topic for the first time will want to read,” Google vice president of engineering Udi Manber wrote in the blog entry. “Google will not serve as an editor in any way, and will not bless any content. All editorial responsibilities and control will rest with the authors.”

Many subjects will have more than one competing knol on the same topic, he said.

“We hope that knols will include the opinions and points of view of the authors who will put their reputation on the line. Anyone will be free to write ... Competition of ideas is a good thing.,” he said.

The project is currently going through a trial phase with a handful of selected users, and the blog entry gave no indication as to when the service would be available for widespread use.

Unlike Wikipedia, each knol will be written by an author or group of authors whose names will be attached to the piece in an effort to create a sense of accountability.

“The key idea behind the knol project is to highlight authors,” Mr. Manber said. “Books have authors' names right on the cover, news articles have bylines, scientific articles always have authors — but somehow the web evolved without a strong standard to keep authors names highlighted. We believe that knowing who wrote what will significantly help users make better use of web content.”

Users will not be able to directly edit pages they way they can with Wikipedia entries, however they will be able to review a knol as well as submit comments or questions and suggest edits.

Created in 2001, Wikipedia claims to have 75,000 active contributors and more than nine million articles in 250 languages. It was the sixth most-visited site on the Web in October, with 244 million unique monthly visitors worldwide, according to ComScore Inc.

Wikipedia entries often appear near the top of Google search lists, however because users can edit the site, article information is sometimes unreliable or false.

Wikipedia is owned by the non-profit Wikimedia Foundation, based in St. Petersburg, Florida.

Wikimedia spokeswoman Sandy Ordonez said the foundation welcomes the Google initiative and hopes the project will adopt a policy of free content.

“The more free content, the better for the world,” she said. “Free content is about freedom — the freedom for anyone to use, study and apply, change and redistribute the work, for any purpose.”