Google's Page Ranking Algorithm
As many of you are probably already aware, Google ranks a page according to the number and quality of links leading to that page. For example, if your page has 100 quality links leading to it, it will rank higher than another page that has only 20 links pointing at it. Quality links come from pages that are themselves "important" (Google's own terminology).
Note that this is not a secret. Google actually publishes information about their ranking algorithm on their website. You can read it for yourself at
http://www.google.com/technology/.