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.

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.