Google ranks all websites, and webpages that it has indexed. It does this on a scale of N/A to 10. If your website has no rank at all, its classed as N/A, then there is 0, 1, 2 all the way up to 10. 10 is the highest page rank, and this goes to the most influential webpages. To give you an idea, at the time of writing this, Facebook has a pagerank of 9, whilst this website has 1.
Whilst Google may update its pagerank on a regular frequency, it is only updated to the end user about once every 3 months. Google does this to stop people learning how its ranking system works, and then ‘reverse engineering’ the process, so they can get their website a rank higher than they deserve.
Some people get really hung up on pagerank, and think if they can get a PR4 site, their life will be complete, they will marry a beautiful person, make loads of money and be at the top of every possible search term for their sites. Sadly, this isn’t true. Pagerank is just Googles way of ranking your site, and has very little, if any, affect on your position within the search results.
No one knows quite how Google calculates pagerank. There are many myths and theories around, and some people believe the old method of ‘number of backlinks’. Unfortunately, this is no longer true, and there are many more factors included, rather than it just being about backlinks.
If you sign up for a webmasters account, or have Google analytics, you are giving Google loads of information about your sites, and what your visitors are doing. This includes;
How many visitors your getting
How long they spend on your site
How many pages they view
Google also looks at who is talking about your site, how many links you have and where they come from, social networks, age of domain, and lots more and tries to work out how influential your site is. This all goes into a complicated maths formula (we presume, as no one really knows) and this then out puts what your page rank should be.
Site or page?
When people say, ‘my website has a PR of 4’, what they really mean is ‘My home page has a PR of 4’. The PR is assigned to a webpage, and not a website. Go onto any website, and (normally) the home page has the highest page rank. They may then be pages within the site with a slightly lower page rank, and some pages of that site that have no page rank at all. This is perfectly common, but it is incredible rare for an entire website to have exactly the same pagerank, when you get above 1.
if your buying a domain with a high pagerank, be careful. You need to be sure that that (unless your buying the site content as well), you fill it with well researched, unique and influential content, or the page rank will be lost at the next update.