What is the difference between dofollow and nofollow?

Is PR the only difference? Will Googlebot still follow and index pages with nofollow? Does google it count as a backlink?

Nofollow links essentially don't exist to Google. They don't follow them or count them as a "vote".

"nofollow" won't pass page rank onto that link. the search engine spiders will follow the link however..

Actually the search engines handle nofollow differently. Google will not follow the link, assign PR to it, or give it weight in its algorithm. Yahoo will follow the link but give it no weight in their algorithm. MSN says they won't give the link any value but it is hard to confirm exactly what they're doing.

Also worth stating its "nofollow" and "follow" not "dofollow". If that wasn't already clear

dofollow, follow, are a waste of time and can be excluded. If that is missing the SE will still index the page. It doesn't need your permission.

You just need to advice it be it via meta noindex, nofollow attribute on links or robots.txt which pages not to index.

Nofollow attribute should be used on links to external sites, that is why it is designed, that you cant vouche for be it blog posts, paid linking etc...

Internal pages you don't want indexed should get the meta noindex in the head of the page or excluded via robots.txt - thwe meta is better though.

you reduce your code bloat that way and helps with indexing.
Jaza

It could be possible that google/yahoo are storing "no follow" links in their secret database.

I dont think we are in a position to reach any conclusion. Google is a secret services search engines which will always try to hide its real ranking secrets

Who cares if they store them? All that matters to us if they use them to rank pages. So far there is no evidence that they do.

no follow means nothing to google..dont pass PR and dont crawl by the spider. it just mainly for advertising your site or increasing your traffic by putting your link into other's site..

I do know that from time to time at least Google slips. I use craigslist a rediculous amount and 1 out of every 25 posts will eventually wind up in my backlinks from Google. Craigslist automatically puts a nofollow link into any link you place in a posting so that shouldn't be able to happen.