A new tool that allows website owners to "disavow" low quality links that might be reducing their PageRank has been added to Webmaster Tools. It comes with the warning "only to be used with caution".

Google's Penguin search algorithm, which was rolled out six months ago, highlighted a new problem - linkspam. 

Instead of low quality links just being a nuisance, given the way the Penguin algorithm treats them you could end up with Google penalizing your site by reducing your ranking. And, we pointed out in a recent Stone Tapes blog, this increased the potential for malicious spammers to do damage by placing low quality links on sites and refusing to remove them. There have even been rumours of sites being blackmailed - pay some money and the low quality links go away.

The problem that Google set out to tackle is that of buying or selling links links with the intention of manipulating PageRank. Other link schemes that can negatively impact a sites's rankings are:

• Excessive link exchanging
• Linking to web spammers or unrelated sites
• Building partner pages exclusively for the sake of cross-linking
• Using automated programs or services to create links.

If Google suspects a site of any untoward link practices the first you may know about it is an "unnatural links" message when you log into Webmaster tools and the way to deal with it is to remove the spammy or low-quality links are quickly and completely as possible.

But what about links you didn't  place - say ones that were deliberatly placed by a malicious third party with the intent of harming you?

This is the problem the Google has now  addressed by providing the new new Disavow Links facility in Webmaster Tools.  It enables you to list low-quality links that you have no control over. However it seems it is not without its risks. If you click on the red Disavow Links button the follow  warning appears:

This is an advanced feature and should only be used with caution. If used incorrectly, this feature can potentially harm your site’s performance in Google’s search results. We recommend that you disavow backlinks only if you believe you have a considerable number of spammy, artificial, or low-quality links pointing to your site, and if you are confident that the links are causing issues for you. In most cases, Google can assess which links to trust without additional guidance, so most normal or typical sites will not need to use this tool.

If you decide to proceed you need to submit a plain text file with one URL per line - but the example shows comments that detail the actions you've already taken to have links removed. The Google blog also states:

So this is indeed a tool that you'll need to use only sparingly and in extreme circumstances. However Google still hasn't made it clear what the exact process is of "disavowing" links.

Does it simply mean that the links you list are no longer used to compute your rank?

Does it mean that it only has an effect if the links on your list have already been identified as low quality and therefore damage your rank?

Given Google's warning about disavowing links potentially damaging your rank, it seems to be the former and this means you have to be very careful what you disavow because you can disavow a positive link just as easily as a negative one.

Althought this problem could be managed in a better way, it is good that Google has provides some sort of solution. At least now you can disarm any blackmailer or competitor damaging your site's reputation.

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