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Disavowing backlinks: should you do that?

What is 'disavow'ing links?

Disavowing a link in terms of SEO is to tell search engines, 'Please do not use this backlink (a link on some other site that has a link to my site) for assessing the quality of my website.'

Why disavow backlinks?

Search engines use many factors for assessing the reputation and relevance of websites (that includes blogs). One of them, a very important one, is backlinks. The argument here is that if a website A is giving a link to website B, A is in some way endorsing website B. It would also mean that A considers B relevant for the anchor text used by it (website A) to give link to B. Since the number of backlinks seems to be a ranking parameter, it is possible to fool search engines to believe that a website getting many (though useless) links is a good website. 

However, many black-hat SEO guys, spammers and even competitors use this very tool of backlinking to harm others' websites and serve their own purpose. They have useless or harmful websites in their store which they use for linking to genuine websites. Such links hurt the reputation of the target website. These links are unnatural and Google etc do not like such links for more reasons than one.

Sometimes bad backlinks arise due to wrong or unethical actions of an SEO guy hired by website owners. In trying to temporarily boost website statistics, they may get irrelevant links by using PBN or paid links or such other means. These become a liability in the long run.

Google's Penguin algorithm updates have particularly focused on the quality of links and it is widely reported that many good websites have suffered badly on account of poor quality links. 

Though search engines lay emphasis on quality of backlinks, the sheer number of backlinks appears to still count, because black-hat SEO practitioners manage to pass through Penguin (and perhaps similar tools used by other major search engines).

How does disavow help in removing bad links?

The most effective action for removing the harmful backlinks would be to get the bad website owners to remove such links. But it is difficult, and they seldom agree because they have put the bad link with a criminal purpose. In some cases, the spammers even ask for money in return for removing those links. Through 'disavow', Google and Bing give webmasters (or website owners) the option to tell them that you would like such a link not to be considered while deciding the reputation of your website. The link remains there but does not hurt your website's reputation in the eyes of Google/ Bing.

Is it safe to disavow links?

Google and Bing have a disavow tool but SEO experts suggest that you use it very carefully so that you do not end up removing good links or branding some natural but low quality links (e.g. from new but genuine websites referring to your website in a natural and good way) as bad links.

Google also advises using this option only if you find a large number of spammy backlinks, as it would ignore a few bad links referring to your site. Perhaps a large number of such links give Google an impression that you yourself have managed those links so as to artificially boost the number of websites linking to you.

So, disavow does not serve much purpose if you do not see unnatural links coming to your website in large number or if your website is visible on search pages as much as it should. However, if you suspect that your website/ blog is suffering because of bad backlinks (for example, it has good content but does not come up high on search pages), you can use the disavow tool and watch the performance of the site for some months.

How to disavow backlinks in a safe way on Google or Bing?

Both these major search engines have tools under their Webmaster Tools (Google now calls its Webmaster Tools website as Search Console). They have option to disavow links one by one or posting a file that contains a list of URLs to disavow.  There is no limit on the number of URLs you disavow. Interestingly, if you upload a new file with disavow links, the earlier file ceases to be considered for disavowing; so, if you want to add links to an already submitted file, add old links again to the new file.

The following two resources are quite good on the subject:

1. Google's own resource on how to disavow backlinks and what precautions to take.
2. An old but very useful guide by Moz on how to disavow links without pain useful tools, and what not to do.