Spamdexing (also known as search spam, search engine spam or web spam) involves a number of methods, such as repeating unrelated phrases, to manipulate the relevancy or prominence of resources indexed by a search engine, in a manner inconsistent with the purpose of the indexing system. Some consider it to be a part of search engine optimization, though there are many search engine optimization methods that improve the quality and appearance of the content of websites and serve content useful to many users.