Cloaking

Cloaking means a black hat search engine optimization technique. In this technique, the content presented to the search engine spider differs to that presented to the browser the user is using. All this can be done by delivering the content based on the IP addresses or the User-Agent HTTP header of the user that requests the page. The user, once identified as a search engine spider, is delivered with a different version of the web page by means of a server-side script. This alternative web page contains content not present on the visible page. The purpose of cloaking is to deceive search engines in order to make them display the page when it would not otherwise be displayed.

Since 2006, there are better methods of accessibility, progressive enhancement included, so cloaking is no more considered necessary.

Often used as a spamdexing technique, cloaking is trying to trick search engines into giving the relevant site a higher ranking.