PageRank is a link analysis algorithm that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set. The algorithm may be applied to any collection of entities with reciprocal quotations and references. The numerical weight that it assigns to any given element E is also called the PageRank of E and denoted by PR(E). The name PageRank is a trademark of Google. Read more on WikiPedia

I have created a seo tool named Pagerank Checker to retrieve the pagerank for any given webpage. Results are retrieved in real time from the google datacenters so they should be accurate enough.

A higher pagerank means a better position for a given keyword in the google search engine. So if a page from your website A has pagerank 3, for example, and another page B (not yours) has pagerank 4, and both pages are relevant to a keyword C, then if somebody searches on google for  the keyword C, the page B will have a higher rank in the result list than the page A, meaning that page B, will have more chances to be visited than page A. In a few word if you want more traffic from Google you need a higher pagerank, higher the pagerank - the better for your website.

I have found an interesting table (TNX.net) showing how many backlinks with a specific pagerank need to point to your webpage to get a pagerank you want.

[caption id="attachment_18" align="aligncenter" width="455" caption="How pagerank works."][/caption]

For example if you want the pagerank 6 for your webpage you need 92414 backinks with pagerank 1 or 18 backlinks with pagerank 6. This theory is not 100% accurate, but it might give you an ideea how pagerank works.

Pagerank is not a stable value. It might change in time because of different factors like backlinks, outbound links, content modification and competitive webpages with similar content like your page. You should check at least once a month the pagerank of the webpage you're interested in, because Google changes the pagerank once in every one or two months.

To visit Pagerank Checker follow this link.