Google updated their PageRank a few days ago, and I discovered that many of my sites had improved! This motivated me to talk a little bit about PageRank. Named after Larry Page, it’s the original metric that defines Google search algorithm. Google scores pages on a toolbar from zero to 10, separating all the real PageRank values of every page these 11 different ranges. This toolbar scale is not linear— it is logarithmic. A page with a toolbar PageRank of six does not have twice as much real PageRank as a page with a toolbar PageRank of 3: its real PageRank value would be much higher.
Though PageRank has nothing to do with relevance for a particular search query, and is not the only factor in ranking in competitive terms, it nevertheless plays a large part in site ranking today. To help you better understand PageRank, I’ve created this diagram that shows how it is determined. Calculating the amount of PageRank that is passed from one site to the next is fairly simple. Every page has an arbitrary PageRank of one. We’ll call this “link juice”. When one site page links to another, the original page passes 85% of its “link juice” to the second page. If linking to one page, it would pass on .85 of its “link juice”, but if it had two outgoing links, it would only pass .42 for each link. Obviously, a very strong page that had many incoming links could have a very high link score, and when it gave a link away, that new link would be very valuable. So, you could have a page with a link score of 100 that had three links to other pages on the web, and each of those links would be worth roughly 28 points. As you can see, this link is significantly more valuable than a link from a brand new page worth just .85. Google calculates a site’s PageRank by adding up all its “link juice”, and by representing that with a number between one and 10and calling that –PageRank!
As you might imagine, it’s exponentially more difficult to achieve each PageRank score. You’d need roughly six times more “link juice” to receive a PageRank of four than you would for a PageRank of three.