Indexing
In short
Indexing is when Google has stored a page in its register. Only pages that are indexed can appear in the search results.
Before a page can show in Google, Google has to find it, read it and add it to the index. Think of the index as an enormous library catalogue. A page that is not in the catalogue does not exist for the person searching, however good it is.
Why pages go missing
Pages can fall outside for thoroughly boring reasons. A setting that tells search engines to stay away was switched on while the site was being built and never switched off again. A new page has no links to it from the rest of the website. Or two pages are so similar that Google only picks one of them.
This applies to AI search too. Google writes that a page must be indexed and eligible to be shown with a snippet to be used as a supporting link in AI Overviews and AI Mode.
How to check your own
Add your website to Google Search Console, which is free. Paste the address of an important page into the URL Inspection search bar at the top. If it says the page is on Google, it is indexed. If it says it is not, you get an explanation and can request indexing. Google says this can take up to a week or two, and that a request is no guarantee.
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