What is Page Rank ( PR ) and How is Calculated

Page Rank (PR) is a Google ranking tool which tells you how Google values your site. Description of PR on Wikipedia. MSN, Yahoo and other search engines use their own ranking methods.

Check the Rank of your site:
- in Google: Googlerankings , Blogflux
- in MSN: Position checker
- in Yahoo: Yahoo Page Rank Checker

Any comments?