Noindex is a meta tag. It’s used to instruct search engines that a particular page should not be indexed, which means that it should not be shown on search engine result pages. Usually, the noindex tag is added to the <head> section of the HTML code for the given page.
If a website owner decides to noindex tag a page after it’s already been indexed and listed by Google, they’ll be removed from Google’s search engine results pages only after the search engine has recrawled through the page. This can take a matter of hours or, in some cases, a handful of days.
Example
<meta name="robots" content="noindex">
