Robots Meta Tag
The robots meta tag tells search engines whether a page should be indexed and whether its links should be followed.
Placed in a page's head, it accepts values like noindex (do not index), nofollow (do not follow links), or a combination of both. It works page by page, unlike the robots.txt file, which works at the site level.
It is used, for example, to exclude a thank you page or a test page from search results without blocking the crawl of the rest of the site. A noindex tag left on an important page by mistake can make it disappear from Google.