by Gabriel Watkins
A 'Page Rank' is a number Google gives to a web page that represents how important Google thinks the page is on the web. When one page links to another, Google considers it to be effectively casting a vote for the other page. The more 'votes' there are for a page across the whole web, the more important that page must be. But that's quite an assumption, isn't it?
The importance of the page that is casting the vote determines how important the vote itself really is, meaning in Google calculations a page's importance comes from the votes cast for it. These votes are then taken into account when the page is ranked.
As a general rule of thumb, Google Page Ranks along with Alexa ratings are the best indicators of how well your SEO work has been going. Granted, the ranking that you appear in on the results for your most important key words is the real indicator, but a strong Google Page Rank will help to boost this position substantially. The more links that you have pointing at your site, the better off you are. That's a basic rule that will apply throughout your SEO operations.
Page Rank matters because it's one of the most influential factors that determine a page's ranking in Google's search results. If you want to have good Page Rank, you'd better make sure people are linking to your site.
leaving the page of the book carelessly open,
something unsaid, the phone off the hook
and the love, whatever it was, an infection.
—Anne Sexton (1928–1974)
Well, don't jump the gun and try to get your site linked from everywhere you can, because Google doesn't count every link. They have started filter out links from known 'link farms' (sites that are nothing but big lists of links), and being linked to or from these kinds of sites will get you penalized by Google. Be careful out there. They have also implemented a new relevance calculator that (true to its name) tries to determine how relevant the links into and out of your site are. The most important factor here is that Google considers long lasting links as more meaningful than a recently published link.
The best way to increase your page rank is to contact people with relevant and complementary content (that is, content that does not compete with your own but that enhances it). These links are most likely to last and they will not only increase your Google Page Rank, but they will also provide relevant hits via the links themselves.
How is PageRank Calculated?
Google calculates the PageRank PR of all pages it indexes, taking into account all the links to and from each site. When a page 'votes' for other pages by linking to them, it shares out some of its PageRank value amongst these pages.
This algorithm means that a link to your site from a page with PR4 (i.e. a Page Rank of 4) and five outbound links would be worth more than a link from a page with PR8 and a hundred outbound links. It's not just the Page Rank of the page that's important, but also the number of links it has.
They who say that women do not desire the right of suffrage, that they prefer masculine domination to self-government, falsify every page of history, every fact in human experience. It has taken the whole power of the civil and canon law to hold woman in the subordinate position which it is said she willingly accepts.
—Elizabeth Cady Stanton (1815–1902)
The more links there are on a page, the less Page Rank value your page receives from them. You should also remember that it takes progressively more Page Rank to move up a level. It is generally pretty easy to achieve a Page Rank of three. Once you achieve a Page Rank of four, your site is getting formidable. Increasing past this mark may prove difficult and will require very important content. Reaching 8+ is very difficult. These ranks are usually reserved for sites that are crucial for the functionality of the internet.
Each time you add a link, or a page that links to you adds a link, you run the risk of lowering your PageRank. Make sure that you have as few links as possible, and so do any sites that are associated with you.
Google repeats its PageRank calculatons many times at each update, and each time the calculation is made it gets more likely to be accurate. Total accuracy can never be achieved, however, because one site's PageRank is entirely relative to the others'. You should understand that the results searchers end up with can really only be properly worked out by Google, because they're the only ones with access to the whole index.