Sidewiki is a tool for Net surfers and bloggers. It appears as an icon in the Google toolbar that opens a window where you can add a comment on the current web page.
We can see this tool as a commenting system similar to that of Wordpress, but added to it the work of an algorithm for ranking the reviews, but less the possibility for the webmaster to filter them.
The Google Blog describes this tool as a means of sharing information between users, implying that the comments are accessible to each other.
So it is a kind of unstructured wiki and a new competitor to Wikipedia. An algorithm similar to the algorithm of the search engine performs the ranking in comments and highlights the most useful, those who come from reliable sources.
The algorithm takes into account the feedbacks from other users, the various comments made by the same author, and generally, the various criteria on trust and relevance.
Update September 2, 2011
Google discontinues Sidewiki and focus on other social activities. This page remains online for history.
How use Sidewiki
The Google toolbar for Firefox or Internet Explorer must be installed or updated.
You must have opened a Google account and be logged in to add comments.
If you check the box saying you are the owner of the page that you are commenting, your comment appear on top of the list among reviews chosen by the algorithm for this page. The box does appear only if the site is registered on Google Webmaster Central. More precisely in GWT.
On option to share the comment and have it available to all users is displayed in a menu.
The commentary can also be sent as a new post if you have a blog on Blogger.
An API is available for webmasters who want to use the content generated by Sidewiki.
Sidewiki and Wikipedia
After having limited the number of external links by the introduction of the no-follow attribute, Wikipedia, victim of manipulations from contributors that add unsubstantiated assertions or even invented quotations, have encouraged the addition of link to references.
Finally articles of the wiki has so many references that they are now like directories of external resources.
Given this fact, Sidewiki will not be different from Wikipedia as a source of information. By combining the notes on a topic we have almost a Wikipedia article!
Sidewiki and webmasters
Webmasters are obviously concerned about the appearance of such a service. Next to their articles, one will found comments on which they have no control, judgments desirable or not, assertions true or false, as in the pages of Wikipedia.
But it's also something they will benefit and that could help them to complement and improve their articles.
It is certain that this new service is something that will change the Web!