Google has launched a new feature in its Toolbar product that opens up a browser sidebar in Firefox and Internet Explorer to let people post and read comments about Web pages they visit.
Called Sidewiki, the product can be used to express opinions about a Web page's content, suggest links to other online resources or provide additional background information.
Sidewiki uses an algorithm to determine the quality of comments and ranks them accordingly, Google said Wednesday.
"[The algorithm] takes into account feedback from you and other users, previous entries made by the same author and many other signals we developed," wrote Sundar Pichai, vice president of product management and Michal Cierniak, engineering lead for Sidewiki, in an official Google blog.
People can comment about the entire content of a Web page or about specific portions of it and then publish their comments to their Twitter, Facebook and Blogger accounts from the Sidewiki interface.
In addition to text, Sidewiki entries can also contain video clips.
People can state whether they found others' comments useful or not by voting "yes" or "no."
Sidewiki also automatically imports to the sidebar other posts published elsewhere but that are relevant to that Web page.
Google eventually plans to make Sidewiki available also on its Chrome browser.
The company is also making a Sidewiki API (application programming interface) available for external developers to integrate Sidewiki content with their applications.
Google offers a somewhat similar feature called SearchWiki to people who use its search engine and log in to their Google accounts.
SearchWiki lets vote up or down search results, remove them and attach comments to them.