Indexation
Last updated September 2026
Indexation is the process by which a search engine crawls a page, evaluates its content, and stores it in the index it draws search results from. A page that has not been indexed cannot rank for anything, which makes indexation the prerequisite that every other SEO tactic depends on.
Before a page can rank, it has to exist in a search engine's index, the enormous database of URLs a search engine has crawled, processed, and judged worth storing. Ranking is a competition among indexed pages; a page outside the index is not in that competition at all, regardless of how well its content, links, or technical setup are built.
The path to indexation runs through three steps: discovery, crawling, and rendering. A search engine first has to find a URL (through an XML sitemap, an internal link, or an external link), then crawl it to read the content, then render it the way a browser would to see what a user actually sees. A failure at any step can keep a page out of the index entirely.
01
Why pages fail to get indexed
Most indexation problems are self-inflicted, introduced during a redesign, a migration, or a CMS change that nobody checked afterward. The common culprits are simple to name and easy to miss:
A noindex meta tag or header left on pages after a staging site goes live
A robots.txt rule blocking the crawler from a section of the site
A canonical tag pointing to a different URL than the one being requested
Thin, duplicate, or auto-generated content the search engine judges not worth storing
Crawl budget exhausted on a large site before the crawler reaches lower-priority pages
Server errors, redirect chains, or slow response times that cause the crawler to give up
02
Confirming indexation status
The reliable way to check whether a specific URL is indexed is Google Search Console's URL Inspection tool, which reports the exact crawl and index status along with the reason a page was excluded if it was. The site: search operator gives a rough count but is not precise enough to audit against; it undercounts and overcounts depending on how Google's index happens to be sampled that day.
03
Why this matters most during a site change
For an agency managing a client's site, indexation problems surface almost exclusively around a launch: a redesign, a platform migration, a URL structure change. A client's organic traffic can collapse within days of a launch if noindex tags or a misconfigured robots.txt slip through from staging to production. Auditing indexation status before and immediately after any structural change is one of the cheapest insurance policies in technical SEO, and one of the easiest to skip when a launch is running behind schedule.
