The noindex HTML meta tag advises automated Internet bots to avoid indexing a Web page. More at Wikipedia
Robots Exclusion Standard - The Robot Exclusion Standard, also known as the Robots Exclusion Protocol or robots.txt protocol, is a convention to prevent cooperating web spiders and other web robots from accessi...
Nofollow - nofollow is an HTML attribute value used to instruct some search engines that a hyperlink should not influence the link target's ranking in the search engine's index.