if you use nofollow tags on the hyperlinks, then the crawlers don’t use those URL’s for PR ranks or SEO in general, it’s like they don’t even exist to crawlers and have no bearing on PR. so does "nofollow" tag on hyperlink prevents you from getting PR?
which is better? using "nofollow" tag on the code or use robot.txt since... robots.txt keeps a page from being crawled altogether, and keeps the page from getting any page rank while you can use nofollow when you want to LOWER the amount of page rank you want to pass to a given page
It's a different thing, at least if you do not do linking between your sites. Nofollow indicates that a link (a href) should not be weighted (I guess the crawler follows it from time to time...). Using robtos.txt excludes the requested parts of the site from the crawl. Rainer
Strangely, a spider will still follow a 'no follow' link, it just doesn't count the link as a vote of confidence in transfering PR. If you dont want to pass kudos or PR to a link use 'no follow'. If you dont want a page indexed then use robots.txt. People used to add links in javascript or form actions in order to hide them from Search Engines but now the 'no follow' is preferred. I wonder if you link to a page that is not indexed due to robots.txt then the PR falls into a black hole? i.e. a valid link leaves the page but the receiving page can not collect it.
Yes. Any inbound link that that has a "nofollow" attribute is of no value. Page rank juice is not passed.
Nofollow links don't passes PR juices... Google has publicly confirmed that links with nofollow have no value whatsoever...but to Yahoo still follow the nofollow.... MSN is still unknown whether they follow it or not..