Over the weekend, Wikipedian-in-Chief Jimmy Wales decreed that all links on the site would be tagged as "No Follow." That means, in essence, that the links become invisible to search engines like Google's. The engines won't take the links into account in ranking search results. Wikipedia is adopting the policy to reduce spammers' incentives to add spam links to the encyclopedia. I wonder, though, if it could also have the effect of reinforcing Wikipedia's hegemony over search results. The sources cited in Wikipedia, many of which are original sources, will no longer get credit for their appearance there, which should cause at least a little downward pressure in their own search rankings (hence providing a little more upward pressure, relatively speaking, for Wikipedia's articles). Although the no-follow move is certainly understandable from a spam-fighting perspective, it turns Wikipedia into something of a black hole on the Net. It sucks up vast quantities of link energy but never releases any.
UPDATE: Search engine expert Philipp Lenssen seems to agree:
Such a change in Wikipedia, with [its] millions of pages – many of which rank excellent in Google and have a high PageRank – has a potentially strong impact on Google search results. Google relies on links to determine its result rankings, and thus huge amount of outgoing links on Wikipedia do their share in influencing that ...What happens as a consequence, in my opinion, is that Wikipedia gets valuable backlinks from all over the web, in huge quantity, and of huge importance – normal links, not “nofollow” links; this is what makes Wikipedia rank so well – but as of now, they’re not giving any of this back. The problem of Wikipedia link spam is real, but the solution to this spam problem may introduce an even bigger problem: Wikipedia has become a website that takes from the communities but doesn’t give back, skewing web etiquette as well as tools that work on this etiquette (like search engines, which analyze the web’s link structure). That’s why I find Wikipedia’s move very disappointing.
Seth Finkelstein also comments on the move.
UPDATE: Amit Agarwal provides an illustration of how the no-follow rule may affect other sites, particularly smaller ones:
Say you discover a cool feature in the iPod (called Stylus) and blog about it. Tomorrow, the Wikipedia contributors append the details of iPod Stylus (your discovery) to the Wikipedia page on iPod. They do attribute your blog but search engines will never see that attribution (or read your blog via Wikipedia) because of the rel=nofollow tag. Now that Wikipedia enjoys higher credibility and trust (read PageRank), the search algorithms will rank the Wikipedia iPod page higher than yours (for queries like iPod Stylus) because the search engine bots are not aware that Wikipedia's content is actually based on your blog page. Result, your site appears after Wikipedia in the "iPod Stylus" search results and you get less or no traffic while Wikipedia gets to enjoy all the fruits of your labor.
UPDATE: Shelley Powers suggests that the best solution may be for search engines to ignore not only links from Wikipedia but links to Wikipedia as well:
Wikipedia is now one of those rare sources on the web that has a golden door. In other words, it doesn't need an entry point through a search engine for people to 'discover' it. If anything, its appearance in search engine results is a distraction. It would be like Google linking to Yahoo's search result of a term, or Yahoo linking to Google's: yeah, we all know they're there but show me something new or different.
Interesting.
UPDATE: The official announcement from Wikipedia says that the no-follow tags are being added "for now," so this may be a temporary measure intended to frustrate an immediate spam threat.
UPDATE: Andy Beard distills the problem nicely. (But what's with those snowflakes?)
