Page Rank Explained
Page Rank or, PR is a number assigned by the Search Engine Google which represnts the relative importance of a web page. A pages PR can range between 0 for an unimportant (in Googles eyes) page and 10 for the most important.
PR is calculated using a 'secret formula' and is used to determine where a webpage will appear within Search Engine Results Pages (SERPS).
It is generally accepted that PR is heavily dependent on the number of Inbound Links (IBL) that a page has. So the more pages that link to your website, the higher the PR of your page will be and the earlier it will come up in SERPS.
The formula is of course more complicated than this. One factor that affects the PR of your page is the PR of the pages that link to it. So for example, a link to your page from a page with a PR of 6 will increase your PR more than a link from a page with a PR of 4. Similarly a link from a page with fewer total links on it will increase your PR more than a link from a page with a large number of links on it. It is also assumed that links from pages that contain content closely related to yours will increase your pages PR more than irrelevant links. Some people even think that irrelevant links and links from pages containing hundreds of other links may reduce your PR.