<meta name="robots"/>

The <meta name="robots"/> tag in HTML 5
<meta name="robots" content="noindex,nofollow"/>

The <meta name="robots"/> tag provides a list of search engine directives, consisting of special predefined terms separated by commas, that provide instructions to search engine crawlers and other robotic user agents.

An alternative to the robots metatag is the robots.txt file.

noarchiveThe value noarchive indicates that a current snapshot of the page should not be permanently stored by the search engine. Some search engines allow viewing a cached version of a web page, which shows how it looked when the page was last crawled.
nofollowThe value nofollow tells search engine robots that they should not access any web pages linked to by the current page.
noindexThe value noindex tells search engines to exclude the current page from their results.
NOODPThe value NOODP indicates that any site information in the Open Directory Project (dmoz.org) should not be used in search engine results.
nosnippetThe value nosnippet indicates that verbatim content from the web page should not be used in a search engine results page (SERP).