The page rank show the current reputation of the site in Google database, Google gives page rank to sites in between 0-10
1. if the page rank is between 7-10 then the site is Excellent rep.
2. if the page rank is between 4-7 then the site is Very good rep.
3. if the page rank is between 1-4 then the site is having normal rep.
pr increases as the site reputation builds up
1. increasing back-links
2. having good traffic rate
3. no error on any page
4. not having expired links
5. the true information provided on site
6. jump rate of the site
7. good comments etc