Cloaking is a black hat SEO technique that enables you to create two different pages. One page is designed for the users, and the other is created for the search engine crawlers. It is used to present different information to the user than what is presented to the crawlers. Cloaking is against the guidelines of Google, as it provides users with different information than they expected. So, it should not be used to improve the SEO of your site.
Some Examples of Cloaking:
- Presenting a page of HTML text to search engines and showing a page of images or flash to visitors
- Including text or keywords into a page only when it is requested by the search engine, not by a human visitor