The English noun "rank" refers to a series, line, order, position, etc. With the suffix "ing" we mean the meaning of "first, highest". The term ranking in computer language is defined as the process which determines the sequence of websites on a SERP after a query. In other words: If the user enters a keyword in the form of a search engine, he gets more or less pages, on which he can find information to his keywords. The order, the websites are headed, is based on an assessment by the search engine index of their entire recorded websites (in Google even PDF files). Since many visitors often click the "first best" site, internet providers want to become one of the first ten on the results pages.