Indexing
Definition
Indexing is the step where a search engine processes a page it has crawled and stores it in its index, the database it searches when someone enters a query. A page that is not indexed cannot appear in results, however good it is.
Indexing sits between crawling and ranking, and each stage can fail on its own. Google Search Console separates 'discovered but not indexed', where Google knows the address and has not fetched it yet, from 'crawled but not indexed', where it read the page and chose to leave it out. The second is the one to read as a verdict on the page. Common causes are a noindex tag, a canonical tag pointing elsewhere, a page too close to another, or content with little to add.
It matters more than it used to. Google lists being indexed, together with eligibility to show a snippet, as the condition for appearing in AI Overviews and AI Mode, and any assistant can only use pages it can find. Check your ten most valuable pages by pasting each address into the URL Inspection tool in Search Console, in both language versions if the site is bilingual.
Not every page should be indexed. Internal search results, filter combinations, thank-you pages and staging copies usually should not be. Submitting a sitemap or requesting indexing asks Google to look. It doesn't oblige Google to keep the page, so fix the reason for the exclusion instead of resubmitting the same address.
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