In an earlier post I said that “The best links are not paid, or exchanged after out-of-the-blue emails–the best links are earned and given by choice.” Given the recent discussions of paid links, I wanted to talk about this issue in more depth.
SEO geeks may remember the SearchKing lawsuit regarding link selling that was filed in 2002 and dismissed in 2003. Or they may have read through our quality guidelines, especially the part that says “Don’t participate in link schemes designed to increase your site’s ranking or PageRank.” Those people can probably guess that Google does consider buying text links for PageRank purposes to be outside our quality guidelines.
But for everyone else, let me talk about why we consider it outside our guidelines to get PageRank via buying links. Google (and pretty much every other major search engine) uses hyperlinks to help determine reputation. Links are usually editorial votes given by choice, and link-based analysis has greatly improved the quality of web search. Selling links muddies the quality of link-based reputation and makes it harder for many search engines (not just Google) to return relevant results. When the Berkeley college newspaper has six online gambling links (three casinos, two for poker, and one bingo) on its front page, it’s harder for search engines to know which links can be trusted.
At this point, someone usually asks me: “But can’t you just not count the bad links? On the dailycal.org, I see the words ‘Sponsored Resources’. Can’t search engines detect paid links?” Yes, Google has a variety of algorithmic methods of detecting such links, and they work pretty well. But these links make it harder for Google (and other search engines) to determine how much to trust each link. A lot of effort is expended that could be otherwise be spent on improving core quality (relevance, coverage, freshness, etc.). And you can imagine how the people trying to get link popularity have responded. Someone forwarded me an email from a “text link broker” that included this suggestion:
Most people use words like, SPONSORS, PARTNERS, FEATURED, ADVERTISERS, ADS and other synonymous terms related to advertisers. Our suggestion is to use ‘different’ titles for these ads. Something like RELATED SITES, COOL SITES, RESOURCES, ALTERNATIVE LINKS and so on.
The email later suggests “to use unique locations for ad links like within content.” At the point where people are recommending ways to make paid links less detectable (e.g. by removing any labels or indication that the links are sold), I wouldn’t be surprised if search engines begin to take stronger action against link buying in the near future.
A natural question is: what is Google’s current approach to link buying? Of course our link-weighting algorithms are the first line of defense, but it’s difficult to catch every problem case in adversarial information retrieval, so we also look for problems and leaks in different semi-automatic ways. Reputable sites that sell links won’t have their search engine rankings or PageRank penalized–a search for [daily cal] would still return dailycal.org. However, link-selling sites can lose their ability to give reputation (e.g. PageRank and anchortext).
What if a site wants to buy links purely for visitor click traffic, to build buzz, or to support another site? In that situation, I would use the rel=”nofollow” attribute. The nofollow tag allows a site to add a link that abstains from being an editorial vote. Using nofollow is a safe way to buy links, because it’s a machine-readable way to specify that a link doesn’t have to be counted as a vote by a search engine.