Search Engine Optimization (SEO) | PageRank

Building Google PageRank

What is PageRank?

Once upon a time, Google came along and changed search forever. They assumed:
A link in page A to page B is a recommendation of page B by the author of A
The 'quality' of a page is related to the number of links that point to it
Applied across the whole web (recursively):
The quality of a page is related to the number of links that point to it, and the quality of pages linking to it.
Thus, the Google founders set out to create an algorithm to reflect these assumptions in search rankings, and PageRank was born. The idealized PageRank formula is actually quite simple:
For each page i pointing to p (the page we're calculating for):
j = i's PageRank divided by the number of pages it points to. This is the PageRank it propagates to p.
b = the sum of all j's (juice received by p).
Just one more minor tweak, and we'll have a formula that's pretty close to what we actually see in the wild: Each page does not actually pass its full PageRank. The published paper on PageRank uses 85%, so that's what we'll use.
PageRank FAQ
Does PageRank Really Matter?
PageRank is less important now than it originally was, primarily because spammers abused the PageRank algorithm, but it's still a factor in how well your page ranks. Nobody can really say for certain why one page ranks higher than the next. It could be good keyword density for the search term, or, perhaps the keyword was used in linktext from another website. All these factors come together into a single ranking score. Asking which factor caused a page to rank is like asking which stone tipped a scale.
PageRank is cool because it's one stone that all the pages on your site can share, and PageRank applies not to a single search term, but to every search term that a page could possibly rank for. A lot of people in the SEO community have been knocking PageRank lately, but in my opinion, the factors that contribute to PageRank are of critical importance to your over-all search engine visibility -- especially for dominating The Long Tail of Search.
How Many Links Does it Take to Reach PRx?
Because link quality is a major factor along with link quantity, there's no single answer. A single PR7 link can give you PR5, while it would take somewhere in the neighborhood of 17,000 PR1 links to accomplish the same feat.
The following table is often quoted in PageRank explanations. I do not know its original source, but it rings true from my own experience.
Number of links required to reach a target PageRank Approximations, only.


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