It isn't the only factor that Google uses to rank pages, but it is an important one.

as far as i know PR is calculated thru backlinks.

Backlinks are very important in terms of Page Rank (PR). It is not the single biggest contibutor (who can say which is? - different strokes), but should definitely be one of your top priorities.

Here is a nice site to assist in managing, growing Backlinks:
http://www.checkmypr.com/

xfranco out

PR is indeed calculated based on the links added to websites but the point is about their quality rather than quantity.

For instance, when you add a link from a PR7 homepage to your site, the result after the PR update could be very different from the time you add thousands of PR zero links to your homepage.

It is not true..it is not only depends on the back link only ..but also the quality and relevance of back link and several other factors:

go through this link it is a nice article on Google page rank:

http://www.smashingmagazine.com/2007...know-about-it/

Indeed there are several factors that contribute to Google's calculation of a webpage's PageRank; one significant source being the volume, credibility, importance and relevancy of the incoming links to the web page, another being the volume, credibility, importance and relevancy of the internal links (from the same domain or sub-domain) to the webpage; commonly known as the internal linking structure.

Let's look at this a bit more. I fail to see what's the PR frenzy is still about. Bear with me ...

A webpage can reach as high as a PR4 simply from the inside of the web site itself (this is quite common); beyond that it appears to require external stimulus; hence comes into the play the power of a corporate blog or additional website(s) dividing the marketing agenda logically. What I'm saying is, you can probably get to wherever you want on the PR scale armed with your own resources. For example, you may want to attain a PR7 status, for whatever reason. You probably could pull off a PR5 or 6 on your own, with the use of enough of your own ingenuity and you may have to maximize in your innovativeness. After that you'll most likely require additional fortitications so ... so eventually you get to PR7 and wonder, where the heck's my prize for this effort ...

Important NOT to get confused between Pagerank and SERPs. I think too often in these forums I see people not understanding the difference between the two. And it's important to understand which is more important.

Focus on good SEO and your SERPs. THIS is what drives traffic to your site.

Pagerank is only a MINOR factor in how Google determines your SERPs. Google considers dozens of factors when assigning SERPs. If you have a good link building campaign focused on your SERPs, it's likely you'll help out your Pagerank anyway. Just don't waste your time focusing on Pagerank. A high Pagerank does not guarantee traffic or good SERPs.

the answer is a defenitely "NO"
google use pr (page rank) to rank/classify a certain site. based on its algorithm, google will determine how popular your site is by monitoring the age of your site, inbound links, traffic and content. the rankings will start from pr0 to pr10.

yes back links are inportant factors for getting a pr ... its one of the inportant factors of ofpage optimazation but there are also many other ways to get a pr or improve a pr