Wikipedia began adding the rel="nofollow" attribute to all of the site’s outbound links over the weekend. The move reportedly comes in response to spammers targeting Wikipedia as a way to increase their search engine rankings. A recently launched spam contest was specifically cited in the decision to add the attribute to Wikipedia’s outbound links.

Wikipedia has experimented with nofollow in the past and the community voted against it, but as Wikipedia continues to grow it becomes an even bigger spam target. Spammers looking to raise their page rank via inbound links continually spam Wikipedia using robots, spiders and even hand editing to get their links onto the site.

Wikipedia’s decision to use the nofollow attribute in outbound links may deter some of the link spam since having a link with nofollow doesn’t help page rank which is the spammers main goal.

The rel="nofollow" attribute was in fact designed for exactly the reasons that Wikipedia has implemented it. Google recommends the tag be used in any situation where users may post public links that cannot be trusted, such as wiki-style editable pages or blog comments.

Unlike the “robots” meta tag which resides in a page’s header and tells search engine robots not to follow any links in the document, the rel tag does not stop Google’s spiders from following the link, it merely tells them not to count the link when calculating the linked page’s ranking.

Naturally not everyone is happy with Wikipedia’s decision.

Critics of the move claim that it will do little to stop spam and argue that it hurts legitimate sites, who may lose search engine ranking, more than it hurts the spammers. Additionally some bloggers are upset because they feel Wikipedia owes its popularity in part to the bloggers who linked to it.

But most of these criticisms don’t hold much water, particularly the shrill cries of but-we-made-you-what-you-are from bloggers threatening to add nofollow attributes to all their Wikipedia links.

If I remember right, links were created for humans to get from one page to another, so regardless of what Wikipedia’s links may mean for page rank, the links still serve their intended function.