Cloaking is a search engine optimization (SEO) method in which the matter offered to the search engine spider is dissimilar from that presented to the user's browser. This is done by deliver content based on the IP addresses or the User-Agent HTTP header of the user requesting the webpage. When a user is identified as a search engine spider, a server-side script delivers a different version of the web page, one that contains content not present on the visible page, or that is present but not searchable. The reason of cloaking is sometimes to trick search engines so they show the page when it would not otherwise be displayed also called black hat SEO. However, it can also be a functional though antiquated procedure for notify search engines of matter they would not otherwise be able to trace since it is embedded in non-textual containers such as certain Adobe Flash components or video.
