By Nate Anderson | Published: January 23, 2007 – 10:52AM CT
The rel=”nofollow” link tag was introduced in late 2005 by Google as a way to fight comment spam on blogs, and it was quickly adopted by the other major search engines and blogging software providers as well. Most search engines give more weight to web sites that are linked to by lots of other sites, the idea being that the number of links is a proxy for the quality of the linked site. Link spammers, realizing that this was the case, bombarded blog comment sections with links, hoping to boost the ranking of their sites. The “nofollow” tag tells search engines not to give any weight to that particular link in calculating a site’s ranking.
Wikipedia’s popularity and its ease of editing made it a desirable target for link spammers, as successfully placing a link in a Wikipedia article could quickly do good things for a web site’s standing on Google or Yahoo or MSN. Most popular blogging software now includes the “nofollow” tag on user comments by default, but Wikipedia has generally resisted the practice, preferring to deal with problems by blacklisting problem sites and relying on volunteer spam-watchers.
Introducing “nofollow” has consequences, after all; it means that legitimate external links don’t get the ratings boost and it brands user-contributed links as untrustworthy by default (which can be seen as working against the basic ethos of the site).
But it’s also another potential tool in the ongoing war against spam. As evidence that the war is alive and well, consider the SEO [search engine optimization] world championship taking place right now. The contest is sponsored by a Swedish company called GetUpdated, and the goal is to register a domain after January 15, 2007, then get it to the top of the results when “globalwarming awareness2007” is entered into the major search engines. GetUpdated is offering prizes, too, including a car. Their goal is to “highlight the advantages of SEO surrounding the advertising community and help sustain the technical development within optimization.”
Wikipedia has already seen increased spamming activity as a result of the contest and has decided that it’s finally time to make the “nofollow” link widespread. In an e-mail on a Wikipedia mailing list this weekend, Brion Vibber announced that Jimbo Wales, Wikipedia’s founder, had asked him to implement “nofollow” on all external links from encyclopedia pages. Vibber noted that he had seen “a fun rumor of a ‘search engine optimization world championship’ contest targeting Wikipedia.”
In Wikipedia discussion pages about the decision, not everyone thought it was the best way to handle link spam. Some posters raised questions about the effectiveness of the policy. Although using the tag will discourage some link spammers who only want to boost their search engine ratings, plenty of spammers don’t care about search results so long as they get plenty of traffic. Because Wikipedia is such a popular resource, spammy links can still provide this traffic.
Update: A longtime Wikipedia editor tells us that user pages already have the “nofollow” tag in place for external links and will continue to use it.