Google Uses Backlinks in at Least Two Ways

contextual back link

Before we get into the nitty-gritty of do-follow (DF) versus no-follow (NF) backlinks, it is important to make a distinction about how Google uses hyperlinks. One way that Google can use the hyperlink is to pass SEO juice. Most people are commonly aware of this fact, that if you have inbound links from high authority sites, they will be valuable in improving your search engine rank. However, it’s possible for Google to use links in other ways. For example, there may be types of links that give you no SEO value, i.e. they will not help improve your search engine position. But, Google may use the link to ascertain relevance. In other words, if the anchor text of the link is the word dinosaur, Google can then ascertain that your site is about dinosaurs. So be aware that links may have value for search engine position purposes while yet other links will help establish the topic of your site. This is important to understand so that you can rank well for the keywords you desire and it helps Google categorize your site with others in the same subject matter.

Now that we understand that backlinks may have value over and above helping your search engine position, we can intelligently consider the distinction of an NF and DF links.

Do Follow in the Old Days

backlinks in the old daysWhen I first started blogging and looking into SEO, I came across the opinions to seek out DF links. Supposedly, these DF links are better because the search engine bots can follow them back to your site and give your site the proper SEO credit for the link. You can do searches and locate blogs and sites that have set their coding to DF. The default, by the way, is that sites are set to NF. The conventional wisdom is that by placing links on DF sites, you get the SEO juice from the search engine bot. This conventional wisdom however is limited as we shall see.
There was and maybe is currently, an advantage to setting your outbound links to DF. In the old days, I set my WordPress sites to DF and promoted this fact on the home page. I also entered these blogs into DF directories. My goal was to increase visitors and by offering DF links in my comments and I had additional traffic as a result.

What about the links from Social Sites?

Note that the social bookmarking sites are all NF sites such as Facebook, LinkedIn, MySpace and others. However, Google carefully tracks your Facebook likes, your Twitter tweets and you Google plus votes as indications of social value. So although these links may be NF, you can see that in fact they have value in establishing the popularity of your site.

Too Many Do Follow Links Does not Look Right

chainsTo take this one step further, should your site have mostly DF links, this appears unnatural to Google. It appears as if you have gone on an artificial back link building campaign to seek out sites that are coded specifically DF. This is of course unnatural and Google will discount the value of these links for your site.
Let me give you an example of suspicious links. Let’s say you place a banner ad on a blog and the banner is in the sidebar. The banner gets associated with every post since every post that gets viewed also displays the banner. If this particular blog has 900 posts, then there are 900 links pointing to your site. Banners and other advertisements are no follow links. That means that the search engine bots will not follow them but of course human beings can click on them and arrive at your site. Should those banner or add links be coded as do follow, Google immediately sees that someone is trying to game the system and you could be looking at de-indexing from their search engine.

The Obvious Value of No Follow Links

Then of course, as mentioned, there is the fact that humans see and follow NF links and this can be quite valuable as per one blogger’s report. He tells how NF links were introduced on Wikipedia to stop the spam content that was being placed on their site. He concludes however that a link from Wikipedia even today still makes your site look more credible and you can get lots of referral traffic from it. One of his websites recently got a link from Wikipedia (his site was credited as a source) on a fairly obscure article, but that single little link still sends around 100 visitors a month. Therefore, be happy to gain quality NF links.

Another blogger reported that a human saw and followed an NF link to his site and then blogged about the site on his DF blog. The post went viral and his post reached the #1 position for his search term. So sometimes, an NF link can morph into DF link value.

What Do Link Studies Show?

But what I like best of all is to share studies, that is tests of actual sites and their link building campaigns and the results. One test indicated that undoubtedly, Google’s bots accounted for the anchor text of NF links in deciding the subject matter of the site. The same test provided hard to refute indications that these links also helped the page rank:
http://www.socialseo.com/blog/an-experiment-nofollow-links-do-pass-value-and-rankings-in-google.html

Here is another experiment, the findings of which corroborate that at minimum, the bots use NF links for relevance:
http://challenge.co/forum/showthread.php/4211-My-Latest-Nofollow-Test

There you have it—DF or NF, a good link is a good link!