to increase the PR of other pages on your site. meaning in this way you can control from which page to pass the pr. it called link scuplating, anyway i dont think this technique is working anymore
You're right... this technique was used a lot but now it's not working. Some websites still use it but it's either legacy or bad design.
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. Using nofollow on these links enables Googlebot to crawl other pages you'd prefer to see in Google's index
The major reason can be that you want to hide some pages from Google, that he does not need to know about. For example your pages that show that you are an affiliate, but not a self-contained business, etc.
BQ, the problem of site-wise duplicate content has disappeared in the beginning of 2010, according to MC.
really? I didn't know that. Thanks for the info I'll have to change it up on some of my sites now. I guess I should read matt's blog more often lol.
ummm no, that's not the reason to use the nofolllow tag. if some pages don't have PR, look at the internal link structure, as no PR is flowing to the page.
i think it shouldn't be used widely on a website , it's allowed only for a few links in each web page as i know
I generally use nofollow on internal links to tell Googlebot which pages I want to receive link juice from other pages. The nofollow attribute is just a method that gives webmasters the facility to modify PR flow at link-level granularity. So many methods would also work (e.g. a link through a page that is robot.txt'ed out), but nofollow on individual links is simpler for some folks to use. There's no stigma to using nofollow, even on your own internal links; for Google, nofollow'ed links are dropped out of our link graph; Google don't even use such links for discovery. By the way, the nofollow Meta tag does that same thing, but at a page level