You have probably discovered that most of your webpages new users is comming from Google and if you have the google toolbar installed you might have noticed the PageRank indicator, which shows the PageRank of the webpage you currently are visiting on a scale from 0-10 (0 is not ranked and 10 is top ranking). The PageRank on a page is calculated based on the rankning of the pages linking to the page by the patented PageRank algorithm. Google has more than 10.000 servers, so it is quite a task to calculate the pagerank, so the pagerank is typically updated monthly - last time was between january 26-29 2003. This update is known as the Google Dance. The previous google dances is listed here. This PDF describes PageRank in 56 pages - so if is abour PageRanking, it is in here! If you want to know how to optimize your site for google, try these google-tips.