A couple of weeks ago, Google announced its “disavow” links tool.
A brief background
Google’s primary indicator of site and page quality is something called a backlink (a link from one website to another). It determines which pages ranking in its search results pages.
Throughout Google’s history, some unscrupulous “SEO”s have abused backlinks by buying them in order to achieve ranking. This is against Google’s guidelines.
With Google’s recent crackdown on link spam though algorithms such as Penguin, the practice of sabotaging competitors by buying low quality paid links has also become prevalent
While Google has always denied that this will harm a website, there is concrete evidence that it does. Google’s launch of the disavow links tool confirms this.