I think it’s time we all agreed that the “nofollow” tag has been a complete failure.

For those of you new to the concept, nofollow is a tag that blogs can add to hyperlinks in blog comments. The tag tells Google not to use that link in calculating the PageRank for the linked site.

In other words, if I post a comment on your blog, and my comment includes a link to my site, people can click on that link to see my site as usual. Ordinarily Google would see that link and view it — as it views most hyperlinks — as an implicit endorsement of my site. This would ever so slightly boost my site’s ranking in Google search results. But if your blog software adds the nofollow tag, Google won’t give my site any added weight at all.

The half-baked idea was that if everyone adopted nofollow, it would quickly make comment spam pointless. The thinking was that comment spam is aimed at creating lots of links to a certain site, thereby boosting that site’s rankings in Google searches. Example: If I fill your comment pages with links to haiku, then maybe Google will start to believe that my haiku site really does have something to do with haiku.

Since its enthusiastic adoption a year and a half ago, by Google, Six Apart, WordPress, and of course the eminent Dave Winer, I think we can all agree that nofollow has done … nothing. Comment spam? Thicker than ever. It’s had absolutely no effect on the volume of spam. That’s probably because comment spammers don’t give a crap, because the marginal cost of spamming is so low. Also, nofollow-tagged links are still links, which means that humans can still click on them–and if humans can click, there’s a chance somebody might visit the linked sites after all. Heck, if we really wanted to eliminate comment spam, why don’t we just get rid of hyperlinks altogether?

Worse, nofollow has another, more pernicious effect, which is that it reduces the value of legitimate comments. Here’s how:

Why should I bother entering a comment on your blog, after all? Well, I might comment because you’re my friend. But I might also want some tiny little reward for participating in a discussion, contributing to the content on your site, and generally enhancing the value of the conversational Web. That reward? PageRank, baby. But if your blog uses the nofollow tag, you’ve just eliminated that tiny little bit of reciprocity. Thanks, but no thanks. I’d rather just comment on my own blog. And maybe, if you’re lucky, I’ll link back to you.

In fact, the solution to comment spam is simple. I’ve used it both on this blog, and on my haiku site. Here’s the step-by-step solution:

Step 1. Automatically moderate any comments that include hyperlinks.
Step 2. There is no step 2.

That’s it. Just throw any comments with hyperlinks into a moderation queue. If you feel like it, you can visit that queue every now and then to let legitimate comments through. Or if you’re busy or cranky, ignore the queue. Either way, no spam will get onto your site (well, almost no spam), spammers’ PageRanks won’t get boosted, and legitimate commenters will still be able to post their comments. And if you moderate up any comments that do have links, the commenters will get the PageRank lifts they deserve.

PS: Hmm, it seems that the great minds behind Technorati also seem to have been involved in nofollow.