What is Google doing to combat the effects of comment spam?

What is Google doing to combat the effects of comment spam? - answered by Matt Cutts

Matt's answer:

CUTTS: We have a question from Jman right in from Melbourne, Australia. Jman asks: “What are Google’s thoughts on blog commenting? Obviously, spammers out there are using this technique to build links. What is Google doing to combat this?” Well, there’s a few different things. One thing we did was we reintroduced what’s known as the nofollow attribute, and that let’s people put a nofollow on links that they consider something that they wouldn’t vouch for, for example, if a third party is leaving links and you really don’t know who that person is, they haven’t registered, they haven’t built up any sort of reputation with you so you don’t know whether you can trust them. That’s exactly the sort of thing where you can use the nofollow link. It’s a very general mechanism. For example, if we were writing blog classifiers to try to find, you know, word press blogs, and movable type blogs, that would work pretty well. It would detect a lot of blog comments, but it might not detect blog comments in, you know, China, Japan, Korea. So, by providing that general solution, something like a nofollow, individual software packages and blog makers who are worried that they might get attacked can add nofollow on the links that are appropriate so that spammer see, okay, this isn’t really going to do me much good. So, that’s something that a bunch of different people work together to bring about. I think that launched in 2005. And it’s kind of nice because even though people might see blog comment and blog spam happening now, it was really getting out of control a few years ago. And you do see other third party tools. For example, there’s a Kismet, movable type also, has anti-spam plugged in. There are a lot of third party services that you can use. Google does do a lot of blog spam and blog comment detection within our own system. So, we have algorithmic ways of trying to detect when people are spamming blogs or when people are trying to spam guest books, or refer a spam or whatever the technique is. So, Google does a relatively good job of making sure that those comments that are done by spammers don’t really do them any good. But you can always take the solution into your own hands by making sure that any links that you think are getting spammed can have the nofollow attribute on them. So, you got solutions you can use yourself and then Google also does a lot of stuff on our site.

by Matt Cutts - Google's Head of Search Quality Team


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