Knol - http://knol.google.com/
A knol is an authoritative article about a specific topic.
Here are some examples of knols. Google Knol is designed to allow anyone to create a page on any topic, which others can comment on, rate, and contribute to if the primary author allows.
As said, the service gets its name from the word "knowledge." A "knol" is a new term that Google has coined to stand for a unit of knowledge, and they're also using that word as the name for pages within the service and the service itself.
Knol pages will be hosted by Google. Authors will have the option to enable Google ads and share in revenue. The pages will be made available to be found through a Knol-specific search as well as through Google itself or via other search engines, as they won't be blocked from spiders. It's likely the service will be found at knol.google.com or some similar standalone address, if it indeed finally launches. As said, a launch might not happen at all -- there's certainly no set date.
They have done about 6 months of Beta testing before release it to public. The other available knowledge websites are Wikipedia, Yahoo Answers, Mahalo, and Squidoo.
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