What is the PageRank?
PageRank is Google's way of deciding a page's importance. It matters because it is one of the factors that determines a page's ranking in the search results. It isn't the only factor that Google uses to rank pages, but it is an important one.
Each site indexed by Google has a PageRank value in the range 1 to 10. A PageRank 10 website is very well seen by Google and this means that the website is very popular. A website with PageRank1 is not very well known by search engines and internet users.
How is this PageRank being calculated?
The PageRank algorithm is not very well known, as most of the secrets behind Google are. Anyway, a lot of possible PageRank algorithms have been published in time, each trying to aproximate as much as possible the current value each site has. All formulas agree that the most important thing in the pagerank calculation is the number of inbound links. Inbound links are the number of links that Google has recorded about your site, from other sites to your site. This number can be found out using a link:www.my-domain.com search on Google or using the Inbound Links Tool.
How important is the PageRank for SEO?
In the "early" SEO days, PageRank was a very important Google optimization factor. Nowadays, the PageRank is not as important as it should be, but it keeps to be a part of the search position ranking algorithm. On the other hand, if you work on increasing your PageRank by increasing the number of inbound links, and you build the inbound links in a smart way, using themed links, your site will get a good search result position. Of course, you need to work on the on-page optimization factors as well.
My website has PageRank 0. How could this be happening?
The PageRank value of all websites are updated once in a while by the so called Google Updates or Google PageRank Updates. If you've created a website, and no such updated occured since then, you might have a PageRank value equal to 0. Don't worry. The next time Google will update the PageRank, your PageRank will increase if you have. Fot now, Google just doesn't have inbound links for your site recorded in it's databases. Just wait untill a new PageRank update will be performed. Usually a PageRank follows an Inbound Links Update, so keep an eye on your inbound links using the Inbound Links Tool.
How can I increase the PageRank for my site?
As mentioned, the PageRank value depends on the number of inbound links your site and your page has. If you want an increased PageRank, first you have to increase your inbound links number. You can do this in several ways: directory submission, blogs, forums, links exchange.