For those of you who adopt the nofollow tag for links, you may want to stop and think before doing this. Research and studies show that nofollow links are actually a root cause for page rank dissipation. Instead of the website / page retaining page rank, nofollow links will now waste pagerank.

Links that are given nofollow attributes on pages will still pass page rank away from the website, this is because of the mass influence webmasters try to achieve by nofollowing chunks of their websites to focus PR on pages or page groups. Although this maybe seen as beneficial, to search engines it is an additional influence of the webmaster to further manipulate rankings rather than trying to acquire additional page rank through good quality pages/content.

The clampdown comes after excessive use of nofollow tags to retain page rank, instead, the nofollow attribute will only work on external outbound links. If website A links to website B with a nofollow link, page rank will not be transferred, however, internal pages will instead waste pagerank.

This is still under scrutiny from some SEO communities, although current research has shown this to be the case by calculating the websites internal link weight against the volume of pages using the page rank formulae. So, think carefully before nofollowing certain pages, it is likely to waste pagerank rather than help to retain it.