Knol was a Google project that aimed to include user-written articles on a range of topics. The lower-case term knol, which Google defined as a "unit of knowledge",[1] referred to an article in the project. Knol was often viewed as a rival to Wikipedia.[2][3][4]
The project was led by Udi Manber, a Google vice president of engineering.[5] It was announced on December 13, 2007, and was opened in beta version on July 23, 2008,[6] with a few hundred articles, mostly in the health and medical field.[5][2]
Knol did not find a significant audience and became viewed as a failure.[3][4] The project was closed on April 30, 2012, and all content was deleted after October 1, 2012.[7][8][4] The Internet Archive has snapshots of Knol archived between July 2008 and May 2012.[9]