前言：Google's PageRank (PR) is a "link analysis algorithm measuring the relative importance" (PR @wikipedia). The importance of PR nowadays is a lot lower than one or two years ago. Nevertheless, PR is the only ranking value that is public to all audience, which means it's the only factor with some transparency. For those who don't know: a PR of 10 is the highest around (like for apple.com), and 0 the lowest - those sites who don't even have a PR of 0 are in a kind of sandbox (a special filter to punish the site) or not indexed by Google.
Please forgive me for being lazy during English lessons @ school as I'm trying my best :)