When we talk about Page Ranking, We have to find out those factors google uses to give page ranking. Google uses more than 250 algorithms to give a page ranking and we do not know all of them, But some factors are that we can identify. Google gives ranking on the basis of popularity of a webpage. If a webpage is popular enough, Google will give higher page rank to that page.
In this article I am giving some factors google uses to give a ranking to a page.