Knol is another Google project which aims to include user written articles on various topics ranging from science medical information, geographical and historical information, entertainment, how-to’s and all.

It was officially announced on December 13th 2007, but opened in beta to public on July 23 2008.
Google defines “knol” as a unit of knowledge.
All contributors to the Knol project must sign in first with a Google account and are supposed to state their real names.

Knol is being described as a competition to sites such as Wikipedia, but in its layout and model, it most closely resembles About.com.

It still has a long way to go to be fairly useful to general public.

Information source: http://en.wikipedia.org/wiki/Knol