Pagerank is based on the number of incoming links to your website. Different web pages pass on different quantities of "PR juice" based on a few different factors. These primarily consist of the PR of the page linking to you and the number of outbound links on that particular page. The ideal website for "PR juice" would be a PR10 website with only your link on it. To get an idea of the value of how the pagerank scale works and an understanding of how it is logarithmic visit the following pagerank table: http://www.kenkai.com/google-pagerank-table.htm
You can start getting backlinks by using social bookmarking sites like stumble, digg, del.icio.us, etc...
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