PageRank is Google’s way of deciding a page’s importance. It matters because it is one of the factors that determine 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.

It is a numeric value that represents how important a page is on the web. Google figures that when one page links to another page, it is effectively casting a vote for the other page. The more votes that are cast for a page, the more important the page must be. Also, the importance of the page that is casting the vote determine how important the vote itself is.  But unlike a democracy a page can have more than one vote and links from pages with high PageRank are given more weight (according to their ranking) and thus help to improve the targets’ PageRank. Google calculates a page’s importance from the votes cast for it. How important each vote is is taken into account when a page’s PageRank is calculated. PageRank was developed by Google founders Larry Page and Sergey Brin at Stanford. At the time that Page and Brin met, search engines typically linked to pages that had the highest keyword density, which meant people could game the system by repeating the same phrase over and over to attract higher search page results.

PageRank is patented by Stanford, and the name PageRank likely comes from Larry Page.

The algorithm of PageRank takes into account entering links, the backlinks, and the links of the site towards other pages. That does not prove only the links that one makes on other sites improves PageRank, because the initial algorithm is not used any more for a long time (according to Google). On the other hand it is confirmed by the sites of search engines that outgoing links, if they are relevant and if they point on sites of references, contribute to select a page at the time of a search.