Wikipedia often catches flak for letting anonymous users waltz in and edit articles, leading to inaccuracies and vandalism other writers can take days to fix in some cases. Google voiced plans to introduce a rival online encyclopedia based on a different concept last December. Known simply as Knol, the service made its debut this week and has been collecting new articles at a growing pace.
From the get-go, Knol doesn't look dissimilar to Wikipedia. You can browse and search articles freely, and if you want to add a new piece, you can just sign up, log in, and start writing. But unlike Wikipedia entries, Knol articles have a fixed author (or group of authors)—usually an authoritative source with a few extra letters at the end of their name. Readers can rate articles, post comments, suggest edits, and even start "rival" articles if they think they can do better. Still, Knol makes it very clear you're reading something from a single source, and it generally shows you the author's picture and credentials at the top right of an article.
Because it emphasizes authors so much, Knol has a somewhat more commercial feel than Wikipedia. Pieces are covered under attribution licenses or plain-old "all rights reserved" copyrights, and contributors can choose to have Google place ads on their articles and get a share of the proceeds. That's not to say there's nothing in there for Wikipedia fans, though: Google also lets writers enable an "open collaboration" mode that allows anyone with a Knol account to modify their work.
You can check out Knol in action at knol.google.com. The service mainly includes entries on medical subjects right now, but contributors have also posted articles on topics like pancakes and toilet clogs.