Google PageRank & Yahoo WebRank, for measuring linkjuice-based authority in search engines...
The ability to calculate link juice is an integral part of modern web search engineering, and the major web search engine companies like Google & Yahoo have given names to their own scales of link juice measurement.
Google uses PageRank, named after Larry Page, the co-founder of Google (see Google's Tech Overview); and Yahoo uses WebRank.
The PageRank of a given webpage can be seen on the little green bar in the Google Toolbar; and the WebRank used to be featured, experimentally, on the Yahoo Toolbar (see archives of the Yahoo WebRank help site), but WebRank is nolonger the subject of public overview.
![[Nested circles, increasing in relative area by approximately 10 times with each step from the centre, in order to depict the relative rarity of each level of Google PageRank link juice.]](pr4-pr10.gif)
An approximate graphical representation of the relative rarity of each level of Google PageRank link juice. See also: full SVG version.
Google PageRank
PageRank is basically just Google's scale for measuring link juice. With each increment of PageRank, the true value of the page increases tenfold.
Have you ever wondered how to make sense of that little green bar that appears on your Google Toolbar when you visit some websites? Basically, it works like this. There are about 10 pages on the whole of the web with a full green bar (a PageRank of 10/10). There are about 10 times this many pages with a PageRank of 9/10 (that's about 100 URLs in total). There's about a thousand pages on the web with PR8 (PageRank 8/10). There's about ten times more PR7s than PR8s. There's 10 times more PR6s than PR5s, and so on. So with each increment of Google PageRank, your page is about 10 times rarer (and 10 times more important).
In total, there are about 100,000,000,000 PR0 pages, which is about a fifth of the amount of pages returned by Googling "www". That's 10*10*10*10*10*10*10*10*10*10*10 PR0 pages. That's a quantity of "one, followed by eleven zeros", which can be called 1011 (10 to the exponential power of 11).
Check out our little picture (above/right), as a graphical reprentation of the respective value of each level of Google PageRank. The black dot in the middle of the left-hand edge (2 pixels' radius & 4px diameter) represents the quantity of PR10 webpages (URLs). The small grey ring around it (5px radius) represents PR9 URLs. The small, black ring (18px radius) represents PR8 URLs. The medium-sized grey ring around it (56px radius) represents PR7 pages. The black circle whose diameter just about fits in the picture's height (178px radius) represents all the pages on the web with a Google PageRank of 6. The bulk of our image is occupied by a segment of a large grey circle (564px radius), and this circle represents the amount of pages on the web that have a PageRank of 5. As you can see, the quantity of PR10 pages (represented by the tiny black dot) is much less than the quantity of PR5 pages, and it gets into silly sizes long before we get to PR1 and PR0 (but feel free to check our how many circles you can fit on your screen, from our SVG version, which requires an SVG-compatible browser like Firefox or Chrome, or IE with an Adobe SVG plugin).
PR9 & PR10
PR10 (PageRank 10/10) is the highest PageRank that any page on the web can have; and PR9 (PageRank 9/10) is the next best (with a tenfold difference). It is the peak of the web, and almost exclusively occupied by the biggest of techno-monopolies (eg Google, Microsoft, Adobe, Yahoo), governmental & academic institutions (eg the Whitehouse, Yale, Princeton). There are about 10 pages on the web with a PageRank of 10, and there are about a hundred on PR9.
See also, examples of PR9 & PR10 websites.
Notes to self...
Make page "/pr9-pr10-sites"
PR8
This is the peak of all commercial presences online, with the exception of only those closely affiliated with PR9 & PR10 sites.
Notes to self...
Check FTSE & Dow companies' websites' positions
PR7
This is the peak of nearly all commerical industries, with the exception of the very most profitable ones, and those affiliated with the biggest academic, governmental & tech-monopoly sites. A PR7 site with great onsite optimisation can still compete with the average PR8, PR9 & PR10 site.
PR6
This is near the top of most industries. PR6 is very respectable, and if well-optimised, can still compete with the average PR7 & PR8 site.
PR5
A homepage Google PageRank of 5/10 is a quite respectable position for an average global organisation, but will not compete at the very top of the most profitable industries unless onsite optimisation is extremely powerful.
PR4
This is respectable for a large, local organisation, or an average, national organisation in an industry that's not extremely profitable.
It's often best for these sites to wait until they reach PR5+ before trying to compete heavily on a global stage.
Matt Cutts defends Yahoo's paidlink directory...
Trading PageRank
Google actively penalise sites which are found to have been buying or selling links that pass on link juice (PageRank). Google refers to these juicy sold links as Paidlinks.
Link trading is a classic black-hat SEO technique, responsible for large quantities of search engine spam, and therefore should be avoided.
In recent years, however, there have been double-standards involved in processes with which search engines have been penalising link-juice traders. So they've regularly updated their policies and are likely to continue to do so for some years. For example, up until October 2008, Google said "submit your site to relevant directories such as the Open Directory Project and Yahoo", but this advice was withdrawn in October 2008.
Matt Cutts talks again...
Matt Cutts talks again...
