Google tag to help prevent comment spam

Lots of comment in the blogosphere overnight about the new anti-spam comment tag that Google announced yesterday.

Here's what Google say:

If you're a blogger (or a blog reader), you're painfully familiar with people who try to raise their own websites' search engine rankings by submitting linked blog comments like "Visit my discount pharmaceuticals site." This is called comment spam, we don't like it either, and we've been testing a new tag that blocks it. From now on, when Google sees the attribute (rel="nofollow") on hyperlinks, those links won't get any credit when we rank websites in our search results. This isn't a negative vote for the site where the comment was posted; it's just a way to make sure that spammers get no benefit from abusing public areas like blog comments, trackbacks, and referrer lists.

This is what it means.

Someone leaves a comment in a post you've written, just like this one that someone did leave in one of my posts:

My personal favorite is <a href="http://www.whatever.nl/">this one</a>.

Nothing at all to do with the subject of the post. But the URL is there so if anyone clicked on it and went to the site concerned, that would count in Google's ranking.

So what would happen with the new Google tag is that the URL in the comment would change to this:

My personal favorite is <a href="http://www.whatever.nl/"rel="nofollow">this one</a>.

The magic bit is the text I've highlighted in red: "rel=nofollow."

It means that while the spam comment will still be there - this tag doesn't actually prevent spam - the spammer will derive no benefit at all in higher search engine ranking from click-throughs. The thinking here is that when the tag is widely implemented, there will be less incentive for spammers to use blog commenting as one of their spam weapons.

Using the tag will be an automatic process - you the blogger don't do anything - with the changes taking place behind the scenes by your blog software. Clearly, this will take some time to be implemented by every software publisher and blog hosting service.

But, in an amazing show of very quick backing for Google's initiative, support for the new tag has already been publicly stated by hosting services Blogger (owned by Google), Six Apart (who own TypePad and, now, LiveJournal), MSN Spaces, Flickr and Buzznet, plus software publishers Six Apart (with Movable Type), WordPress, Bloxsom and Blojsom. Rival search engines Yahoo and MSN Search have also stated their support for it.

Any idea that will help lessen the negative effects of comment spam is just great, especially when an initiative like this has such widespread and immediate support.

As a TypePad user, though, I'm increasingly interested in how to prevent comment (and trackback) spam in the first place, something you just cannot do with a hosted TypePad blog, as I commented recently. Using a Captcha system, for instance.

Also see these excellent discussions about comment spam in the IT Kitchen back in October - The Problem with CAPTCHA and Anti Trackback and Comment Spam Methods.

Prevention is surely better than cure.

Comments

[Tyme]

It will be interesting to see if comment participation decreases because the page rank incentive is taken away. It will also be interesting to see if those site owners who were active commenters see a drop in their page rank. If they do, it's a shame because legitimate commenters should not be punished.

[Anders]

Hi Neville. I think you've got some of the details wrong on how this tag will prevent comment spam.

You wrote "the spammer will derive no benefit at all in higher search engine ranking from click-throughs".

Google doesn't actually measure click-throughs from site to site. Rather, it looks for how many links exist on the web that point to a website (backward links), and derives the ranking from these "endorsements".

So now, when counting the number of links to a website, Google won't include the ones noted with "nofollow" in the final tally.

[Neville Hobson]

Tyme, you're right - as I understand it, the 'nofollow' tag will affect every URL written in a comment, so legitimate ones will also be part of this.

One thing that's not clear (to me, at least) is whether the tag also applies to the URL you enter when you identify yourself when leaving a comment to a blog post. Or is it just the URL within the area in which you write the comment.

If the former, then that's definitely going to concern some people. It will impact the whole linking concept of blogs.

Anders, thanks for that clarification. I guess my using the phrase 'click-throughs' was the wrong one to use here. But I understand what you've explained.

[Anders]

I think it would be both... both the URL you can leave, and any link you include in the comment itself.

Should be a great tag to use. Now if only Google could figure out a way to deliver an electric shock to spammers through their keyboards...