About Google Page Rank

Google Page Rank
It's a number from  0 up to  10 , Important, high-quality sites receive a higher PageRank
PageRank Explained

PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page's value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves "important" weigh more heavily and help to make other pages "important."

Important, high-quality sites receive a higher PageRank, which Google remembers each time it conducts a search. Of course, important pages mean nothing to you if they don't match your query. So, Google combines PageRank with sophisticated text-matching techniques to find pages that are both important and relevant to your search. Google goes far beyond the number of times a term appears on a page and examines all aspects of the page's content (and the content of the pages linking to it) to determine if it's a good match for your query.
Google's complex, automated methods make human tampering with our results extremely difficult. And though we do run relevant ads above and next to our results, Google does not sell placement within the results themselves (i.e., no one can buy a higher PageRank). A Google search is an easy, honest and objective way to find high-quality websites with information relevant to your search.
How to know the PageRank of a website?
1- You can use our web tool click here to know the PageRank for any website .
2- You can use our power  tool click here to know the PageRank for 100 websites at once  .
3- You can install Google toolbar
Note :  Some parts of this article taken  from Google