(1) Also known as stealth, a technique used by some Web sites to deliver one page to a search engine for indexing while serving an entirely different page to everyone else. There are opposing views as to whether or not cloaking is ethical. Opponents see it as a bait-and-switch, where a Web server is scripted to look out for search engines that are spidering in order to create an index of search results. The search engine thinks it is selecting a prime match to its request based on the meta tagsthat the site administrator has input. However, the search result is misleading because the meta tags do not correspond to what actually exists on the page. Some search engines, such as Lycos, Hotbot and Excite, even ban cloaked Web sites. Proponents of cloaking assert that cloaking is necessary in order to protect the meta data, as only the spider is supplied with the meta tags.
Also see How Web Search Engines Work in the Did You Know . . . ?section of Webopedia.
(2) In e-mail distribution, cloaking is the act of masking the name and address of the sender so that the recipient does not know who sent the e-mail.