• by Shankar Gupta , January 20, 2005

In a move that will likely send ripples through the search engine optimization and marketing fields, Google Tuesday proposed a new tactic to stop so-called "comment spamming."

Comment spamming is the term for companies or affiliates filling the comment section of a Web site or log with links to their own sites. This technique has the effect of driving up a site in Google's natural search rankings, by creating links on outside sites.

Google declined to comment on its proposal, instead referring inquiries to the Google Blog. Matt Cutts, a Google software engineer, and Jason Shellen, a blogger program manager, penned an entry there that explains the decision.

"If you're a blogger (or a blog reader), you're painfully familiar with people who try to raise their own websites' search engine rankings by submitting linked blog comments like 'Visit my discount pharmaceuticals site,'" the pair wrote. "This is called comment spam, we don't like it either, and we've been testing a new tag that blocks it."

Already 10 big names in blogging software have signed on to use the tag to block out comment spammers, including Blogger, LiveJournal, Six Apart, and MSN Spaces. The tag works by stopping the Google crawlers from following the tagged link and crediting it to the linked site. Without the credit to the linked site, the site doesn't move up in the natural search rankings, and the spammer loses the payoff of doing it in the first place.

The vice president of the Search Engine Marketing Professionals Organization, Dana Todd, said that when Google makes these sorts of changes to its engine, the entire industry generally takes notice. "They're a big stick, particularly since they own Blogger. All they have to do is flip a switch and the underlying engine changes," she said.

However, Todd said, there were already some controls in place for many bloggers to stop comment spamming. "Bloggers have the ability to set controls on the comments where you can either autopost, or it has to go through a review, or users can't post at all," she said. Nonetheless, the practice had become common in certain categories, and bloggers who didn't use these methods and let commenters post at will could find themselves in "cleanup mode," Todd said.

The most widespread categories for comment spamming, Todd said, were in competitive keyword areas. "Pharmaceuticals, any of your financial services, payday loans, things like that. Things where a lot of affiliates are reselling leads for very competitive keyword space," she said.

Todd declined to comment on Google's specific tactical methodology, because she said SEMPO's membership may include companies hurt by this change. But she also said that content spamming hurts the industry. "Search engine marketing will only be effective if users continue to trust the search engines as a relevant information source," Todd said.

Google's proposed tag is set to be included automatically in the blogs of writers publishing with the 10 blogger software makers who have signed on to the plan. Google also plans to expand this tag onto other areas vulnerable to comment spamming, like guestbooks, visitor stats, or referrer lists, according to the company blog.

And it's not only Google crawlers that will be ignoring e-mail spammers, the Google blog said. MSN's MSNBot crawlers and Yahoo!'s search crawlers will also recognize the tag, and not follow and credit the linked site, Cutts and Shellen wrote on the blog.