SAN FRANCISCO, USA: Google Inc opened its website Knol to the public on Wednesday, allowing people to write about their areas of expertise under their bylines in a twist on encyclopedia Wikipedia, which allows anonymity.

"We are deeply convinced that authorship -- knowing who wrote what -- helps readers trust the content," said Cedric DuPont, product manager for Knol.

The name of the service is a play on an individual unit of knowledge, DuPont said, and entries on the public website, knol.google.com, are called "knols". Google conducted a limited test of the site beginning in December.

Knol has publishing tools similar to single blog pages. But unlike blogs, Knol encourages writers to reduce what they know about a topic to a single page that is not chronologically updated.

"What we want to get away from is 'this last voice wins' model which is very difficult if you are a busy professional," DuPont said.

Google wants to rank entries by popularity to encourage competition. For example, the first knol on "Type 1 Diabetes" is by Anne Peters, director of the University of Southern California's Clinical Diabetes Programs.

As other writers publish on diabetes, Google plans to rank related pages according to user ratings, reviews and how often people refer to specific pages, DuPont said.

Knol focuses on individual authors or groups of authors in contrast to Wikipedia's subject entries, which are updated by users and edited behind the scenes.

Knol does not edit or endorse the information and visitors will not be able to edit or contribute to a knol unless they have the author's permission. Readers will be able to notify Google if they find any content objectionable.

Knol is a hybrid of the individual, often opinionated entries found in blogs and the collective editing relied on by Wikipedia and other wiki sites.

The service uses what it calls "moderated collaboration" in which any reader of a specific topic page can make suggested edits to the author or authors, who retain control over whether to accept, reject or modify changes before they are published.

In its early stages, Knol remains a far cry from Wikipedia, www.wikipedia.org, which boasts 7 million collectively edited articles in 200 languages.

Google signed a deal with Conde Nast's New Yorker, giving Knol authors the rights to use one of the magazine's famous cartoons in each Knol posting. Google will allow Knol writers to run ads on their entries and will share income with them.

DuPont said that rather than competing with Wikipedia, Knol may end up serving as a primary source of authoritative information for use with Wikipedia articles.

"Knols will fill gaps on what we have on the Web today. That is what we hope," DuPont said.

(Additional reporting by Michele Gershberg in New York)