Spamdexing

Spamdexing (also known as search engine spam, search engine poisoning, black-hat search engine optimization, search spam or web spam) is the deliberate manipulation of search engineindexes. It involves various methods, such as link building and repeating related or unrelated phrases, to manipulate the relevance or prominence of indexed resources in a manner inconsistent with the purpose of the indexing system.

Spamdexing could be considered a part of search engine optimization, although there are many SEO methods that improve the quality and appearance of the content of websites and serve content useful to many users.