Despite
this many people seem to get it wrong! In particular “Chris
Ridings of www.searchenginesystems.net” has written
a paper entitled “PageRank Explained: Everything
you’ve always wanted to know about PageRank”,
pointed to by many people, that contains a fundamental
mistake.early on in the explanation! Unfortunately this
means some of the recommendations in the paper are not
quite accurate.
Any good web designer should take the time to fully understand
how PageRank really works - if you don’t then your
site’s layout could be seriously hurting your Google
listings!
[Note:
I have nothing in particular against Chris. If I find
any other papers on the subject I’ll try to comment
evenly]
How
is PageRank used?
PageRank
is one of the methods Google uses to determine a page’s
relevance or importance. It is only one part of the story
when it comes to the Google listing, but the other aspects
are discussed elsewhere (and are ever changing) and PageRank
is interesting enough to deserve a paper of its own.
PageRank
is also displayed on the toolbar of your browser if you’ve
installed the Google toolbar (http://toolbar.google.com/).
But the Toolbar PageRank only goes from 0 – 10 and
seems to be something like a logarithmic scale:
|
Toolbar
PageRank
(log base 10)
|
Real
PageRank
|
|
0
|
0
- 10
|
|
1
|
100
- 1,000
|
|
2
|
1,000
- 10,000
|
|
3
|
10,000
- 100,000
|
|
4
|
and
so on...
|
We
can’t know the exact details of the scale because,
as we’ll see later, the maximum PR of all pages on
the web changes every month when Google does its re-indexing!
If we presume the scale is logarithmic (although there
is only anecdotal evidence for this at the time of writing)
then Google could simply give the highest actual PR page
a toolbar PR of 10 and scale the rest appropriately.
Also
the toolbar sometimes guesses! The toolbar often shows
me a Toolbar PR for pages I’ve only just uploaded
and cannot possibly be in the index yet!
What
seems to be happening is that the toolbar looks at the
URL of the page the browser is displaying and strips off
everything down the last “/” (i.e. it goes to
the “parent” page in URL terms). If Google has
a Toolbar PR for that parent then it subtracts 1 and shows
that as the Toolbar PR for this page. If there’s
no PR for the parent it goes to the parent’s parent’s
page, but subtracting 2, and so on all the way up to the
root of your site. If it can’t find a Toolbar PR
to display in this way, that is if it doesn’t find
a page with a real calculated PR, then the bar is greyed
out.
Note
that if the Toolbar is guessing in this way, the Actual
PR of the page is 0 - though its PR will be calculated
shortly after the Google spider first sees it.
PageRank
says nothing about the content or size of a page, the
language it’s written in, or the text used in the
anchor of a link!
Definitions
I’ve
started to use some technical terms and shorthand in this
paper. Now’s as good a time as any to define all
the terms I’ll use:
|
PR:
|
Shorthand
for PageRank: the actual, real, page rank for each
page as calculated by Google. As we’ll see
later this can range from 0.15 to billions.
|
|
Toolbar
PR:
|
The
PageRank displayed in the Google toolbar in your
browser. This ranges from 0 to 10.
|
|
Backlink:
|
If
page A links out to page B, then page B is said
to have a “backlink” from page A.
|
That's enough of that, let's get back to the meat.
