On Tuesday 16th October 2012, Google announced the launch of its new Disavow Links Tool. This new tool is intended for the use of experienced webmasters who are well-informed of aggressive SEO techniques. The tool aims to help solve the problem of “unnatural links” pointing to your site due to manual spam action.

Disavow links

Building lots of low quality backlinks to your website is not good SEO practise and can be interpreted as black hat SEO. As it has a negative effect upon your page ranking, creating “unnatural links” is sometimes done as a means of attack from competitor sites. The Google Disavow Links tool aims to give website owners a chance to have these links discounted by their spiders.
The tools states “If you believe your site’s ranking is being harmed by low-quality links you do not control, you can ask Google not to take them into account when assessing your site.”

If you website contains links to unreliable sites, you will be notified of this by Google via email. The email will detail some of the types of links that are considered unnatural up to a maximum of three. These emails will not detail all of the bad links that you have associated with your website however; it is up to you to investigate them yourself.

It is important to note that the vast majority of people should not need to use this tool as they will not have a large number of unnatural links. The process takes weeks to be completed from the time your list of disavowed links is submitted to the time they are ignored by Google as your site will have to be crawled and indexed again, which takes time. You also need to be aware that reinstating a link that has been disavowed takes even longer than disavowing it in the first place; therefore please ensure that it is definitely the right decision to make before you disavow a link. The tool is designed to be used by experienced webmasters who have a good working knowledge of aggressive SEO techniques.

This statement is clear that Google are trying assist people with problems relating to a large volume of low quality links:-

https://www.google.com/webmasters/tools/disavow-links-main

Disavow links

The Google Disavow Tool is to be used as a last resort to stop your website being associated with unnatural links. Removing the link completely from the web is the most effective way of improving your page ranking; this is done by contacting the person responsible for the other page and having the link removed manually. There will always be a small amount of people that are unreachable and this is why the disavow tool has been introduced. This tool does not remove the link, rather suggests that Google ignore it.

If you believe your website ranking has being harmed by low-quality links that you do not control then you can ask Google not to take them into account when assessing your site rankings.

For more information about this go to:
http://googlewebmastercentral.blogspot.co.uk/2012/10/a-new-tool-to-disavow-links.htm