Authors have been invited to submit content to Knol, Google's own wiki, seven month after the company first said that it was going to set up a rival to Wikipedia.

However, although the concept is quite similar to that used by Wikipedia, Google said it is not looking to compete harshly with the established site. Google said it is focusing on highlighting the authors who submit articles to the site. Each 'Knol' (which means a unit of knowledge) will have a single author or group of authors whose name(s) will appear with their contributions, Google noted in a blog post.

"The web contains vast amounts of information, but not everything worth knowing is on the web," Google said. "An enormous amount of information resides in people's heads: millions of people know useful things and billions more could benefit from that knowledge. Knol will encourage these people to contribute their knowledge online and make it accessible to everyone."

Knol will include a new concept that Google is calling "moderated collaboration" where any reader can make suggested edits to a knol, which the author can choose to accept, reject or modify for inclusion on the site, Google said.

Knol also includes various community tools to allow users to submit comments, ratings or write a review of Knol. Mashable blogger Adam Ostrow said that because Knol allows authors to insert AdSense ads on their knols and earn money based on clicks "this sounds a lot less like the community collaborating on authoritative articles (Wikipedia) and a lot more like a potential land grab to create content for keywords."

However, he acknowledged that offering the ability for anyone to comment or review an article raises or lowers the authority of that article and should keep "would-be opportunists" at bay.

"In giving a single author control over each Knol and its edits, it's hard to imagine the service will be as authoritative as Wikipedia (which, many would argue has its own biases)," Ostrow added. "Meanwhile, Knol could still be a huge traffic generator for Google and steal visitors from Wikipedia if it's integrated in search results - something Google has not been shy about doing with other properties like YouTube."

Danny Sullivan, a blogger at Search Engine Land, added that the best way to describe Knol is Wikipedia with moderation. "The collaborative advantage to Wikipedia is also its disadvantage," Sullivan noted.

"Since anyone can contribute, some introduce factual errors or overtly vandalise articles. It's one reason that Wikipedia is considering moderation."

However, Sullivan added that he is concerned that hosting Knol content will set up inherent conflicts that will start to erode trust users have in Google.

"By hosting this content, it plays too much in the content owner space when its core business is supposed to be driving traffic outbound to others," Sullivan noted. "I can see the value in Knol's toolset and the potential it might offer to help collect further knowledge. So I'll give Knol the benefit of the doubt - that it will perhaps occupy a space not being filled, rather than push others aside."