How indexing works
Getting into search results happens in stages, and indexing is the second one. First a search engine has to find and fetch the page, which is crawling. Then it processes what it fetched — reads the text, follows the links, works out the topic, decides whether the page is a duplicate of something it already holds — and, if it judges the page worth keeping, stores a version of it. That stored copy is the index entry. Only after that can the page be considered for any search at all.
None of the stages is guaranteed. A page can be crawled and not indexed, which is the situation that confuses most site owners, because the server logs show Google visited and the page still cannot be found. Indexing is a judgement, not an automatic consequence of publishing, and a search engine will decline to store a page it considers duplicated, empty or not worth the storage.
Why indexing matters
It is the gate everything else stands behind. Keyword work, content, links and speed improvements all assume the page is in the index; if it is not, none of them can produce a single visit. When a new service page brings in nothing at all, the first question is never what it ranks for — it is whether it is indexed.
The reverse matters too. Pages you never intended to be public — internal search results, filtered listings, staging copies, thank-you pages — can be indexed and end up competing with the pages you care about, or showing a stranger a page meant for a customer who has just paid.
Where indexing goes wrong
The blocks fall into two groups. Some are instructions you gave without meaning to: a noindex directive left on after a redesign, a robots.txt rule blocking a whole folder, a canonical tag pointing somewhere else, or the WordPress setting that discourages search engines and stays switched on after launch. These are quick to find and quick to fix.
The others are judgements. Google may report a page as crawled but not indexed, or discovered but not yet crawled, which usually means the page adds nothing to what is already stored, sits with no internal links pointing at it, or belongs to a set of near-identical pages generated automatically. Submitting the URL again does not change that verdict. The page has to become worth indexing.
How to act on it
Check before you speculate. Search Console’s URL Inspection tool tells you whether a specific page is indexed and, if not, which of the reasons above applies; the Pages report groups the same information for the whole site. Read the stated reason first, because the fix for a directive and the fix for a quality judgement have nothing in common.
For directives, remove the block and request indexing once. For judgements, give the page a reason to exist: make it genuinely different from its neighbours, link to it from a page that already gets crawled often, and include it in the XML sitemap. If a large share of a site sits unindexed, the problem is usually structural rather than page by page, and a technical SEO review will find it faster than repeated submissions.