Knol is a Google service that lets people share knowledge. Many refer to Knol as Google’s version of Wikipedia. The Knol project consists of user-written articles on a range of topics. Contributors can write and publish any number of Knols on the same or different topic. Readers with Google accounts can rate, comment on, or suggest edits to the Knols, similar to blog comments.
See also “Google Products and Services” in the Quick Reference section of Webopedia.