Cloaking is a black-hat SEO technique whose purpose is to deceive search engines into displaying a page that wouldnt be displayed otherwise. Basically, the fraudulent user is presenting one page to the search engine spider, while another is presented to the visitors. Cloaking is achieved by delivering different content depending on the IP address (or User-Agent HTTP header) of the users. Although its commonly used for spamdexing purposes, cloaking is sometimes useful as a way of presenting the search engines with the content that was invisible to them for some reason. Still, the used of cloaking for this purpose is considered outdated, as other more-efficient methods have been available for more than a decade.