Index

Meaning

An index is the large database in which a search engine stores information about pages it has crawled and understood, so they can be shown in results. It works like a library catalogue: it is an organised record of what the search engine learned, not the web itself. Google states that indexing is not guaranteed, and a crawled page may be left out because of a noindex instruction, duplication or thin content. Search Console's page indexing report shows why pages were excluded. See also: Crawler, Noindex, Canonical URL, and the guide How Search Engines Crawl, Index and Rank Pages.