- PageRank was invented by Larry Page, one of the founders of Google.
- PageRank is a measure of importance NOT relevance and is used to assign a numerical value to web pages.
- PageRank of a given webpage increase when other web pages link to it.
- Relevance and importance influence rank, just because a page is important does not mean it is relevant.
- Toolbar PageRank goes from 0 to 10, Real PageRank goes from 0.15 into the millions.
- Toolbar PageRank is just an indication and is not accurate, in fact two pages with the same Toolbar PageRank will most probably actually have very different Real PageRank.
- PageRank measures importance relatively by ranking every page on the web in order of importance.
- PageRank has been described as voting sytem, whereby one page votes for another by linking to it.
- The formula for determining PageRank is as follows: PR(A) = (1-d) + d (PR(T1)/C(T1) + … + PR(Tn)/C(Tn))
- A page does NOT directly lose PageRank by linking out, it just passes on its importance with a vote.
- When a page passes PageRank it only passes on 85% of it.
- The maximum amount of PageRank in a system cannot exceed the total number of pages in that system, so for a 5 page website the total possible PR is 5.0.
- The total PageRank of a system can be less than the maximum, this is usually due to a poor linking structure.
- Every page in a system should have an inbound and an outbound link.
- By creating more internal links to a page of a site you can increase the PageRank of that webpage, effectively more internal pages are voting for it.
- By removing internal links between unimpotant pages of a system we can decrease the PageRank of those pages but increase the PR of more important pages.
- You can create links between pages using JavaScript so humans can use them but search engines cannot, thereby not distributing PageRank throught them. However this is changing and it is rumoured Google is starting to interpret the code in JavaScript.
- Using nofollow is recommended by Google as a way not to pass on PageRank.
- Google uses over 200 ‘signals’ to determine the importance of pages on the Internet and PageRank is one of them – you can read more about what Google has to say about this here.
- ‘The Anatomy of a Large-Scale Hypertextual Web Search Engine’ is the paper by Sergey Brin and Lawrence Page provides more information PageRank and Google.