Web Spam
Web spam consists of billions of pages of content that have been deployed in an attempt to be included and ultimately to rank in search engines. These sites are designed with a single purpose: to attract visitors and get them to click on advertisements or affiliate links.
Web spam is created by so-called “black hats,” who attempt to circumvent the TOS laid out by the search engines and generate content that will rank. The key to success for modern web spammers is to find a way to place their content onto a site that has earned the trust of the search engines, or to garner enough links from trusted sites for the site to rank for the targeted term.