Search indexing is the process search engines use to crawl web pages, store their content, and surface them in search results. A page does not need to be actively promoted or visibly linked from a current site menu to remain discoverable if search engines have already indexed it.
In cyber security, this matters because retired or forgotten pages can keep distributing files long after a site migration, including installers, scripts, or documents that should have been removed. Attackers may also rely on indexing to make malicious landing pages easier to find, or to expose sensitive files that were never meant to be public. Defenders use indexing behavior to spot stale assets, verify that decommissioned content is truly gone, and search for cached or resurfaced copies of risky downloads. If a page still appears in results, it can continue to look legitimate to users even after the underlying support path is obsolete.