geekay - 3:59 am on Oct 10, 2013 (gmt 0)
The Google Content Guidelines lists the following three uses:
– Untrusted content
– Paid links
– Crawl prioritization (Search engine robots can't sign in or register as a member on your forum, so there's no reason to invite Googlebot to follow "register here" or "sign in" links.)
But look at the way Wikipedia, Facebook, Twitter, blogs, forums etc. are utilising the nofollow. To me it appears that the vast majority of nofollows are used in a way contradicting the G Guidelines. Confusing.