Black hat SEO attempts to improve rankings in ways that are disapproved of by the search engines, or involve deception. One black hat technique uses text that is hidden, either as text colored similar to the background, in an invisible div, or positioned off screen. Another method gives a different page depending on whether the page is being requested by a human visitor or a search engine, a technique known as cloaking.
Black hat seo is one of the search engine technique, by this we can promote our website into internet marketing through searhc engines, but search engines never encourage this technique. Because which is against the search engine guidelines.