Nofollow was introduced back in 2005 and came about as a reaction to blog spam comments. Believe it or not, SEO professionals used to try and manipulate Google’s PageRank on their sites just as they try to manipulate, well, everything. Nofollow basically tells Google (or any other search engine that supports this attribute) not to vouch for the target link. Whereas it was previously used in the page-level meta tag (), it’s much more common to see it used on a per-link basis now.