Meta robots tag
The meta robots tag is a line of HTML that tells search engines whether to index a page, follow its links and show snippets from it.
The meta robots tag is a line of HTML in a page's head that tells search engines what they may do with that page. It can keep a page out of the results, stop them following its links, or limit how much of the page they quote. It looks like this:
<meta name="robots" content="noindex, nofollow">robots.txt decides which pages a bot may read. The meta robots tag decides what a search engine does with a page once it has read it.
The common rules
Google lists the rules it supports in its robots meta tag documentation. The ones you'll meet most:
noindexkeeps the page out of search resultsnofollowasks search engines not to follow the links on the pagenosnippetstops any text from the page being shown in resultsmax-snippetcaps how many characters can be quotednoarchiveasks that no cached copy be kept
You can name one search engine instead of all of them, for example <meta name="googlebot" content="noindex">. For files that aren't web pages, like PDFs, the same rules go in an HTTP header called X-Robots-Tag.
For example, Fernhill Coffee adds noindex to its order confirmation pages, so they never appear in search. It leaves its brewing guides with no robots tag at all, which means everything is allowed.
The meta robots tag and AI search
At Google, these rules reach the AI features too. Google says that nosnippet and max-snippet control what can be shown from your page in AI Overviews and AI Mode, and a page with noindex can't be shown as a source there. Its guide to AI features explains the controls.
Other AI platforms mostly publish rules about robots.txt instead. Check each company's own page about its bots before you rely on a meta tag to keep a page out of its answers.