PageRank is a registered trademark and patent for Google from January 9, 1999 that protects an algorithms family used to assign of numerical form the relevancy of the documents (or web pages) index-linked by a search engine. Its properties are much discussed by the experts in optimization of engines of search. The system PageRank is used by the popular search engine Google to help him to determine the importance or relevancy of a page. It was developed by the founders of Google, Larry Page (this algorithm receives his name) and Sergey Brin, in Stanford’s University while they were studying the sciences of the computing.
PageRank trusts in the democratic nature of the web using its vast linkage structure as an indicator of the value of a page in particular. Google interprets a linkage of a page A to a page B like a vote, of the page A, for the page B. Google looks beyond the votes volume, or linkage that a page receives; also he analyzes the page that expresses the vote. The votes expressed by the “important” considered pages, that is to say with a high PageRank, they cost more, and help to make other “important” pages. Therefore, the PageRank of a page reflects the importance of the same one in the Internet.