Google, Yahoo and MSN support "nofollow"? What's that?

Three cheers for Google, Yahoo, and MSN (and the smart chaps at Six Apart too) for solving one of the most annoying elements of running a Weblog or discussion board nowadays: random or rude comments or trackbacks that are intended purely to sneakily add links to their sites on your own.

I've written about blogspam before, actually, if you want more background (and examples), including What are Weblog Trackbacks?, What does this Blogspam comment mean? and How can I delete blog comment spam easily? Comment spam is a challenge for all of us in the blogosphere.

In a nutshell, the problem is that if you enable the links in comments added by others to your site, or even just link their name to their site, you're inviting unscrupulous spammers to add posts purely to gain a link.

To see how simple the solution is, let's peek at some HTML. A hypertext link in HTML looks like this:

<a href="some URL">text that's linked</a>

The change that the three big search engines announced today is the support for a new attribute called rel with a specific value of nofollow. The previous link would be blindly followed by a search engine crawler (for example, Googlebot), and the linked site would gain some PageRank from the source site. With this new attribute, however, links are not followed by the spiders and PageRank is not transmitted. Here's how that link would look in this brave new world:

<a href="some URL" rel="nofollow">text that's linked</a>

Six Apart, the company that makes Movable Type, has announced that they've already updated TypePad, and that LiveJournal is going to implement it for comments from people who aren't friends. Other Weblog and related systems that have announced support include Blogger, WordPress, Flickr, Buzznet, Scripting News, blojsom and Blosxom.

For Movable Type users, there's a new nofollow plugin that you'll need to download and install. Fortunately, it's only 4K total (a tiny Perl script, actually) and it's worth doing right now, while you're thinking about it.

For the really geeky, the new plugin changes the behavior of links in the tags <MTPings>, <$MTCommentAuthorLink$>, and <$MTCommentBody$> and, far cooler, also lets you enable the automatic tagging of "nofollow" to any URLs encountered in any other MT tag by adding the attribute nofollowfy="1". Are you tired of the links in your articles themselves giving other sites PageRank? Then you could use <$MTEntryBody nofollowfy="1"$> and it'll never happen again (though I don't know why you'd do this, honestly!)

I've installed the plugin on this Weblog, so if you're so inclined, pop over to one of my articles where there are comments and use "View Source" in your browser to confirm that I now do indeed have the snazzy new rel="nofollow" attribute in comment links off my site.

And, finally, is it going to work? I dunno. There are some definite problems with this strategy, not the least of which is that it means that if my friends and colleagues pop by and post an erudite comment - or write their own article that trackbacks to mine - I would like to give them some of my PageRank goodness, but now I can't. You're all thrown into the 'spammer scum' box, like it or not. Also, having it as an add-on is like Microsoft solving security problems with a system patch: it only works if every single person installs it and in this case, I'm sure that even three months from now there'll be a statistically significant percentage of MT, WordPress and other self-hosted Weblogs that will not support "nofollow", and as we've learned in the last few years, spammers are happy to send out a million messages for a handful of positive responses.

Nonetheless it's clear that something has to be done about blogspam, and I applaud the search engines and weblog teams for working together to at least make some progress in this direction, however suboptimal it may be.