Search Engine Spam are pages which users created deliberately to trick the search engine for promotions such as, offering inappropriate, redundant, or poor-quality content. Inappropriate content is content not related to the actual search query.
The process of abusing certain loopholes in search engine algorithms to excess - tactics such as invisible text, overuse of keywords and 'doorway pages' simply don't work anymore and are severely penalized by all major search engines.
Search Engine Spam are pages created deliberately to trick the search engine into offering inappropriate, redundant, or poor-quality search results. Inappropriate content is content not related to the actual search query. An extreme example is an adult-content site that places the keywords "Disney" and "Barney the Dinosaur" on its pages to trick visitors into coming to the site. Redundant content is the process of delivering the same, or very similar, content repeatedly to the search engines. Affiliate programs, cloaking, and doorway pages are common marketing strategies that deliver redundant content to the search engines.