PR means page rank for those of us that those not know what PR means. Page Rank is what Google uses to determine the importance of a web page. It's one of many factors used to determine which pages appear in search results. Page Rank is a link analysis algorithm, named after Larry Page (Google founder), and is used by the Google Internet search engine to 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.
I don’t actually know exactly how Google calculates or measure which hyperlinked set of documents or website to assign page rank to but I will say that it gives credit to site that have good back-links from authority site. So focus on building quality back links with quality articles not quantity and you too will get there one day.
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