Google algorithm
The "Google algorithm" is the mechanism that the Google search engine based upon which is still unknown among surfer and webmasters.But basically there are two main parts to the Google algorithm, the first is its text matching system whereby Google tries to find pages relevant to what the searcher has entered in the search box. The second and equally important part of the algorithm is of course the Google patented Pagerank™ system.
I'll first go through how to make your pages relevant by discussing the text matching part of the algorithm.
Google gives a lot of "weight" to the title tag when searching for keywords. It is therefore vital to make sure your most important keywords or keyphrases appear within this tag. It seems to work best if you've other words in your title tag too after your keywords, but try to remain under 35-40 characters.
I imagine many of you know this already but Google does not use meta tags such as the keywords meta tag or the description meta tag. This is because the text within these tags can't be seen by visitors to a website. Therefore Google feels these tags will be abused by webmasters placing lots of unrelated words in them in order to get more visitors.
This lack of support for meta tags means that Google creates your description from the first few lines of text on your page. This in turn means that you've to have your keywords and phrases right at the top of your webpage, if Google finds them your page becomes more relevant, if however it doesn't find them the rest of your page has to work harder to become relevant. To see an example of what I mean scroll back to the top of this page and you'll notice keyword rich wording similar to:
Google submitting tips, ranking high at google.com, Google ranking tips, pagerank algorithm, Google algorithm guide.
The above text includes keywords and keyphrases related to the theme of this page. Now when people search for any of those keywords or keyphrases this page is much more likely to be near the top of the results than a page that doesn't imply this technique.
Google considers keyword density in the body of a page for determining relevancy too, so make sure your keywords and phrases appear a couple of times throughout the whole page. Don't go overboard though, a density of 6-10% seems to work best.
Google has recently been noticed to give a substantial amount of "weight" to words appearing between the various header tags. These are tags designed to help you split up sections of your page, so this approach by Google seems to make sense. The header tags go from the smallest to the biggest,the bigger the heading tag the more relevent your page will become for the words within it. It is for this reason that you should always try to have your most important words within these tags as often as possible throughout your page.
Other advice about making your page relevant would be to make as many keywords appear within bold tags as you can. In the past Google has been known to index text in alt image tags, whether they still do or not I don't know but it couldn't hurt to include keywords in these tags anyway.
One final tip on page relevancy is the point on having your keywords and phrases in links which point to your site. It's a good idea to have the linking text contain your keywords as Google even says itself in its description of its Pagerank technology that it analyzes pages that links come from.
How much keyword laden links matter is anyone's guess. I have however noticed a lot of sites which give the HTML code to visitors who want to exchange links do include keywords in the actual linking area. You should do this too on your links page, say something like "if you want to link to this site, please use the following code". The code would of course have your most important words in the actual link text and your less important words in the accompanying description of your site.
sources from David Callan(http://www.akamarketing.com/google-ranking-tips.html)
Google Pagerank formula
The dampting factor
The damping factor is the amount of your PR which you can actually pass on when you vote / link to another site. The damping factor is widely known to be .85, this is a little less then the linking pages own PR.
PR(A) = (1-d) + d(PR(t1)/C(t1) + ... + PR(tn)/C(tn))
In layman's terms PR(A) is the Pagerank boost your page A will get after being linked from someone else's site (t1). PR(t1) is the pagerank of the page which links to you and C(t1) is the amount of total links that (t1) has. It is important to know that a pages voting power is only .85 of that pages actual PR and this voting power gets spread out evenly between all sites it links to.
Imagine http://www.akamarketing.com was linked by XYZ.COM's link page which had a PR of 4 and 9 other links, here's how the formula should look like:
PR(AKA) = (1-.85) + .85*(4/10) PR(AKA) = .15 + .85*(.4) PR(AKA) = .15 + .34 PR(AKA) = .49 To sum up my site would get an injection of .49 PR after being linked from a page with a PR of four and 9 other links.
Let's say I was linked from a site with a PR of 8, double the previous example's amount, which had 15 other links, a total of 16 outbound links, my boost would be:
PR(AKA) = (1-.85) +.85*(8/16) PR(AKA) = .15 + .85(.5) PR(AKA) = .15 + .425 PR(AKA) = .575
The above two worked examples show that not only is the PR of the linking page important but what is also important is how many other sites are also linked to from that page.
I think we've had enough maths stuff for now, just remember that the name of the game is to get as many links from pages with high PR and few other links. The more of these links you get the more your PR will grow and the more your rankings will improve for your relevant keywords.
sources from David Callan(http://www.akamarketing.com/google-ranking-tips.html)