"Black hat" search engine optimization generally seeks to exploit the weaknesses of search engines in order to boost a site's ranking on results pages. These techniques often rely on deception, redirection, and other artificial means to generate results.
For example, a black hat SEO specialist might create hundreds of pages filled with keyword-rich gibberish for search engines to find and parse, or they might post meaningless comments on hundreds of blogs, all linking back to the main Web site. It can be tempting to employ black hat techniques to promote Web sites, especially when it produces dramatic short-term results. However, search engines always attempt to out-think the black hat SEOs, and the results are therefore short term. In fact, using deceptive techniques can get you banned from search engines and permanently damange your ranking.