Questions

Page Rank is a web site rating system, developed by Google, where sites are given a number, between 0 and 10 according to their importance on the Internet.
Page Rank of 3 or higher is generally considered the minimum before a link from the site or an ad placed on it can be commercially viable.
Page Ranks fluctuate, over time - for example, at the time of writing, Netcells.net have a Page Rank of 5, BBC.com and GettyImage.com have page rank of 7, Creative Handbook (chb.com) has Page Rank of 4.
There are a number of sites where you can check the Page Rank, such as ›Madsubmitter.com.