What it looks like
Noindex is a small tag in the head of a page, the part visitors do not see:
<meta name="robots" content="noindex">
It says: you may read this page, but do not keep it in the search results. Most site builders offer it as a setting for each page, often labeled "hide from search engines". The same instruction can also be sent by the server as a header called X-Robots-Tag, which is useful for files such as PDFs.
Why it matters
- It keeps the wrong pages out of search. A thank-you page after a form, internal search results and test pages are common cases.
- It works on one page at a time. The rest of your site is not affected.
- It is not a lock. Anyone with the address can still open the page. Use a login for anything private.
- It can be left on by accident. A tag left over from a test version is a common reason a page is missing from Google. That is a problem with indexing, not with your content.
How it works with robots.txt
Noindex only works if the page can be crawled. Google has to visit the page to see the tag. Crawling is controlled by a different file, robots.txt. If that file blocks the page, Google never reads the tag.
A page does not vanish the moment you add the tag. It drops out after Google crawls it again, which can take days or weeks.
How to check yours
- Open the page, right-click and choose "View page source".
- Search the source for
noindex. - If you find it on a page that should be in search, switch off the setting in your site builder and save.
- In Google Search Console, paste the address into the URL inspection bar to confirm that indexing is allowed.
The lesson crawling and indexing, explained simply covers the full path from publishing to the search results.