Google claims the service, which has been kept under wraps in private testing, is different to Wikipedia in a number of ways. Specifically, it encourages writers to use their real names and stand behind their articles. It will also offers users the possibility to generate income from their work via Google ads.
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"Every knol will have an author, or group of authors, who put their name behind their content. It's their knol, their voice, their opinion. We expect that there will be multiple knols on the same subject, and we think that is good," Knol product manager Cedric Dupont and software engineer Michael McNally said in a blog.
Wikipedia, on the other hand, has a culture of anonymity in which contributors rarely use their real names, and no ads appear on the site.
In addition, Knol apparently will have more controls over submissions and edits than Wikipedia. In Knol, readers can suggest changes to articles, and the authors have the final word on whether to accept or reject the feedback. "This allows authors to accept suggestions from everyone in the world while remaining in control of their content. After all, their name is associated with it," the Google officials said.
"Readers will also be able to rate articles and write reviews of them."
In Wikipedia, anyone can make changes to articles and have them appear instantly online.
Although in the blog posting knols are described as "authoritative articles about specific topics, written by people who know about those subjects," a Google spokesman said that anyone can write an article.
"Google will have no advance knowledge of the content of a knol and we will not be doing editorial screening of content posted by users and authors," he said.
In addition, Google will encourage authors to use their real names, but will not require it, he said. Google will give authors the ability to have their identity confirmed via a telephone or credit card verification process. Articles penned by these authors will appear with a 'verified' stamp, he said.
Another difference is that in Wikipedia all content is licensed under the GNU Free Documentation License. This means that Wikipedia content can be copied, modified, and redistributed, as long as the new version extends those same freedoms to others and acknowledges the authors of the Wikipedia article used.
NEXT PAGE: More differences between Knol and Wikipedia
Google has gone head-to-head with Wikipedia after finally releasing Knol - a user-generated online encyclopedia, which was first announced in December last year.
In Knol, authors will get two options for licensing their work. They may choose to reserve some rights using a Creative Commons licence. They also may opt for a traditional copyright licence format to reserve all rights.
"We want to give authors a choice and provide them with an option to publish content in the manner they desire. For some authors, it is important to make their work freely available to the world with a minimum of legal restrictions, while others prefer the 'all rights reserved' model the spokesman said.
Knol is far from revolutionary, considering its similarities not only to Wikipedia but also to other sites like Squidoo, so it remains to be seen whether the Google entry will attract a critical mass of contributors and readers, said Gartner analyst Andrew Frank.
"It's a long shot, if you had to give it odds on whether this will change the world or not," he said.
What's clear is that Knol is another example of Google's power and resources, since not many companies would dare attempt to compete against such an entrenched player as Wikipedia, he said. "It's interesting and certainly shows how Google is one of the few companies with the scale to be able to do an experiment like this without being intimidated by Wikipedia," Frank said.
Although the roster of Wikipedia and Knol contributors will overlap to an extent, Knol will likely attract a different type of author as well - those who want to take advantage of the marketing and revenue opportunities the Google service offers, said industry analyst Greg Sterling of Sterling Market Intelligence.
This has its pros and cons. It may yield articles of excellent quality, but the model will likely sacrifice the collective participation on individual entries that Wikipedia fosters and that results in a generally effective quality control and community policing, Sterling said.
In terms of layout, Knol at first glance seems more user-friendly and appealing than the bare, academic-journal look of Wikipedia, and this might help the Google service attract readers, Sterling said.
Jay Walsh, spokesman of the Wikimedia Foundation, Wikipedia's parent organisation, declined to comment about the competing Google service, but said the group is "always happy" when information is made freely available to the public "under any of the free content licenses".
"The Foundation's mission is to increase the amount of free knowledge globally, and to help bring that knowledge to audiences in as many formats and methods as possible, both on the internet and in off-line formats. To that end, we're always pleased to see other organisations undertaking similar, free knowledge mission work," Walsh said.