The amount of advertising revenue generated by sites is perhaps the ultimate metric for measuring the business potential of Web sites and brands. The top three search engine companies (Google, Yahoo, and Microsoft) are expected to generate about €42 billion in search and display advertising revenue worldwide in 2014 (eMarketer, Inc., 2014f). In contrast, social network sites in 2014 are expected to generate about €12.9 billion in advertising revenue worldwide (eMarketer, Inc., 2014g). Social network sites are the fastest growing form of Internet usage, but they are not yet as powerful as traditional search engines/portals in terms of ad dollars generated. A part of the problem is that subscribers do not go to social network sites to seek ads for relevant products, nor pay attention to the ads that are flashed before their eyes (see chapters 6 and 7).