PageRank is a set of algorithms in Search Engine Optimisation that assigns numerical weightings to documents or web pages indexed by a search engine. PageRank attributes are very much a focal point for SEO experts. The system of Page Ranking is established and used by the popular search engine to determine a page's relevance or importance. This system was developed by the Google. PageRank uses a unique type of the web by utilising its vast link structure as a signal of an individual pages value. Ranking interprets a link from page one to page two as a vote, by page one, for page two.
Defining or explaining the PageRank in another way, a PageRank works by resulting from a ballot among all the other pages on the World Wide Web about the importance of the page. A hyperlink to a page counts as a vote of support. The PageRank of a page is defined and depends on the number and all pages that link to it that are known as incoming link. A page that is linked by many pages with high rank receives a high rank itself. In fact PageRank is very simple, but when a simple calculation is applied hundreds or billions of times over the results can seem complicated. PageRank is also only part of the story about what results get displayed high up in listing. For example there is some evidence to suggest that some search engines are paying a lot of attention these days to the anchor text when deciding the relevance of a target page. PageRank is still part of the listings story though, so it's worth your while as a good designer to make sure you understand it correctly.
The total PageRank will go up for each page it adds to the web site which you are building but the average will remain the same. If you want to concentrate on the PageRank into one or a few pages then hierarchical linking will do that. If you want to average out the PageRank amongst the pages then fully meshing the site will do that. Getting inbound links to your site is the only way to increase your sites average PageRank. The distributed PageRank amongst the pages on your site depends on the details of your internal linking and which of your pages are linked. If you give outbound links to other sites then your site's average PageRank will decrease. Again the details of the decrease will depend on the details of the linking.
The PageRank of each page depends on the PageRank of the pages pointing to it. But we won't know what Page Ranking those pages have until the pages pointing to them have their PageRank calculated. PageRank can be calculated using a simple iterative algorithm, and corresponds to the principal eigenvector of the normalised link matrix of the web. It seems strange but, basically, each time we run the calculation we are getting a closer estimate of the final value. So all we need to do is remember each value we calculate and repeat the calculations lots of times until the numbers stop changing much.