A few years ago to combat blog comment spam, the search engines implemented no follow backlinks. These changes wreaked havoc for big business and small business SEO. These no follow backlinks were suspected of having no SEO value because they don’t pass PageRank from the linking site. It now appears that although they may no pass PR, they do have value. In the recent SEOMoz Search Engine Ranking Factors report, a correlation exists between ranking and the presence of no follow links.The ratio of no follow to do follow links appears to be a search engine ranking factor. If do follow links greatly outnumber no follow links, the site or page link profile may seem unnatural. The search engines expect that in the normal course of link getting, links from both do follow and no follow sites are normal. If your site link profile has a very high ratio of do follow links, you may need to get more no follow links from social media sites, no follow blogs and other sources to balance your profile. What About Authority?
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SEO – A Link Is A Link?