The priority given to the placement of a link on the results page of a Web search. Google became famous for its page ranking system, known as "backlinks" and based on how many other sites on the Web link to a site, and how popular the linking sites are based on traffic. The concept is that if very prominent sites link to a site, the site must have great value.

In addition, the content and organization of the Web pages are also criteria used in the page ranking algorithm. Most importantly, search engines change their algorithms from time to time so that pages cannot be mocked up permanently to fit the search engine's criteria. See search engine optimization, Google bomb and social bookmarking.