January 25, 2005, 9:41 AM — Web logs, or blogs, have emerged as a very significant influencing factor on search results. Millions of blog entries are posted daily, which makes them a timely source of information on the relevance of information on the Internet.
Unfortunately, spammers quickly figured this out, and many web logs now suffer from comment link spam as a result. Read the comments on these blogs and you'll find link spam, comments that link to other sites using popular search phrases. These comment links do nothing to add to the dialog at the site, are completely off topic, and are generally used to promote junk.
Comment spam not only is annoying within blogs, but it bumps up the page ranking of disreputable pages, making it harder for searchers to find legitimate results for popular search phrases.
Don't Follow This Link
To combat the influence of comment spam, Google has come up with what may be the most rapidly adopted de facto standard in the history of the Internet, the "nofollow" link attribute. In a nutshell, it's an attribute that can be added to web page links that tells search engines that they can be ignored.
When indexing a page, search engines normally follow links, and use them to help rank the importance of pages. The nofollow attribute lets web builders control what links search engines will consider important.
Google suggests that sites update their software to add the "nofollow" attribute automatically wherever that a user can add their own links.
Currently many web applications let users add links like this:
Visit my < a href="http://www.hack_yr_pc.com/" >britney spears< /a> site.
To users and search engines, it looks like a link for a popular search phrase. Unfortunately, the link can point to a spammer's site.
Google's proposal is to change user-added links to look like this:
Visit my < a href="http://www.hack_yr_pc.com/" rel="nofollow" >britney spears< /a> site.
The "nofollow" attribute tells search engines to ignore the link. Adding this attribute to user links eliminates the links' value to spammers, while retaining the value of links added by site owners.
Google suggest that this distinction between links added by site owners and user-added links be adopted for any piece of software that allows others to add links to an author's site, including guest books, visitor stats, or referrer lists.
Web Standards, in About an Hour
The "nofollow" attribute may be the first standard created in "Internet time". Google suggested the simple change several weeks ago, and discussed it with other major search engine companies. MSN Search and Yahoo have already committed to adopt it.
Because comment spam is such an annoyance, blog software makers are quickly adopting it. Many vendors have announced that they will support the new attribute:
* LiveJournal
* Scripting News
* Six Apart
* Blogger
* WordPress
* Flickr
* Buzznet
* blojsom
* Blosxom
* MSN Spaces
Because the change is easy to implement, and helps maintain the search engine relevance of pages, companies should consider modifying their applications to include the "nofollow" attribute wherever they allow users to add links to their pages.
ADDITIONAL RESOURCES
Working Together Against Blog Spam
A Defense Against Comment Spam
