Link entering towards a page of a website. If the B page makes a link towards the page A, then B is a backlink of A. The number of backlinks and the PageRank ™ of these backlinks constitute one of the criteria employed by Google in the positioning of Web pages on the requests of its visitors. The more the A page includes backlinks with well PageRank ™ and with a topic close to his, the more the PageRank ™ of the page A will be well and better will be the popularity of this page, will with a positive impact on the positioning of this last by Google. Hence the importance of the installation of an appropriate exchange of links’ strategy (A and B make a reciprocal link towards each, causing a mutual benefit for every part).