Here is a short summary. 1. Follow link is the link that pass PageRank (PR) and authority power to the website that linking to, while Nofollow link will not pass both PR and authority power to the destinate website linking to anyway. 2. Follow link will be in a common html format, while Nofollow link will be attached as "nofollow". See the example below Follow <a href="http://www.domain.com">Link</a> Code (markup): Nofollow <a href="http://www.domain.com" rel="nofollow">Link</a> Code (markup): 3. Both Follow and Nofollow links are still being crawled by Googlebots anyway. Googlebots do crawl to see the destinate only purpose, but still, the nofollow will not pass anything. 4. Please be noted - Yahoo Slurp do not know about "nofollow" and they will crawl and pass everything even "nofollow" attached.
When you say which should you use, what are you referring to? If you building backlinks, ones without nofollow are obviously best. (there is no follow tag) You want the PR. If you are talking about links on your sites, it does not matter, unless you want to cut down on spammed links people put on your site/blog. nofollow has been abused now in so many ways it was never intended. Stephen C
Both give you links at the end of the day, only follow links also help with google rankings, which are more sought after, google being the biggest search engine around.
Follow links are the best, because they help you raise in SERPs, but nofollow links help you too, with direct traffic
SXPERM that's an excellent explanation for newbies. The fact is that BOTH types of links have their benefits. For example say you manage to get a no follow link on a site with high traffic volume, whilst you're website ranking won't receive any benefit at the next PR update from that site, you may still get a good volume of visitor traffic. No follow can also be good on your own site for limiting the amount of link juice you give out to other sites. I use them on all my affiliate links.