Introduction to Nofollow

As we've just announced, we'll be supporting the new rel="nofollow" attribute for comment and TrackBack links with our platforms. With the introduction of the new spec, it's worth reviewing the initiative for Professional Network members who'd like an overview of the entire effort. * What is nofollow? The HTML specification allows a tags for hyperlinks to include a rel attribute. This attribute is used to specify a link type describing the relationship between the document hosting the hyperlink and the document that is the target of the hyperlink. * Is this valid HTML? Yup. Though the rel attribute has been relatively obscure (it's used in XFN and Technorati's tags, but it's not exactly the prom queen of HTML) it's completely valid in both HTML and XHTML. Some might quibble about the semantics of "nofollow" as a link type, but it's clearly not as evil as comment spam. * So, this solves comment spam? In a word, no. But it makes things a lot better. For both comments and TrackBacks, we believe this removes much of the incentive (in PageRank or relevance ranking) for creating comment spam. But some users might not upgrade or install plugins to enable support, and there will always be some websites that accept user-submitted content without filtering it. For a more comprehensive overview of the comment spam problem, and why addressing search engines is a key part of solving the issue long-term, take a look at the Six Apart Guide to Comment Spam that we've published, which talks about the solutions that can be implemented in weblog tools like Movable Type. * What's user-submitted content? Comments and TrackBacks are both examples of content that's not published by a site's owner and that cannot always be verified as safe. For this reason, it's useful to flag links in user-submitted content in a manner that lets search engines distinguish them from links created by weblog authors. * Where else could I use this? If you have parts of your site that aren't published or managed through your publishing tool, you might want to update them to include rel="nofollow" on any links that were submitted by readers or by applications. For example, a list of referrers that's automatically generated would be a great place to add the rel="nofollow" attribute. * How does it work? In Movable Type, we've released a plugin to enable nofollow support, and for LiveJournal and TypePad, support will automatically be enabled as a seamless update for these hosted services. In all cases, links in TrackBacks and comments will have the nofollow value automatically appended to links. In the case of LiveJournal, links from anonymous commenters will be removed completely, and LiveJournal does not yet support TrackBack. * How does this affect Movable Type template tags? If you install the Movable Type Nofollow plugin, the <$MTCommentAuthorLink$>, <$MTCommentBody$> and < MTPings > tags are modified. In each case, Nofollow.pl will intercept the content produced by these tags and alter any hyperlinks it finds, adding a "nofollow" relation ("rel") attribute to them. In the event that a hyperlink already has a "rel" attribute, the "nofollow" relation is added to the front of the list. You can also use a new global tag attribute provided with this plugin. The attribute is named "nofollowfy". You can apply it to any Movable Type tag to achieve the same effect described above. For example, if you had a plugin which displayed your site referrer information, you could use a tag similar to < MTReferers nofollowfy="1" >. * Hasn't this been tried before? How do we know it'll work? Not really. Our own Brad Choate talked up the idea of restricting search engines a few years ago, but until the recent upswing in comment spam, there hadn't been much progress on this. Even after this initiative, there's still no way to flag an area of a page so that search engines won't index it. We're hoping to keep progressing on this front in the future. There's also room for improvements in granularity of control over how rel="nofollow" is applied. For example, sites using TypeKey or other services for authentication could refrain from adding the nofollow directive for authenticated commenters. Or you could choose to have the directive removed for approved commenters or TrackBacks. * What else can I use rel for? As we mentioned above, both XFN and Technorati Tags use the rel attribute, but it's still fairly obscure. The HTML spec also allows for the rev attribute, but that one's almost never seen in the wild. We're pretty excited about some of the uses for these attributes, and we'll be talking more about them in the future. * How else can I help fight comment spam? Follow the steps outlined in the Comment Spam Guide. Make sure your friends do the same on their weblogs. And, if you've got great ideas, come join our team and help clean up the web.