Page indexing is whether Google has crawled a page and stored it in its index, so it can appear in search results. A page that isn't indexed gets no impressions or clicks, however good it is. Search Console's URL Inspection tool shows a page's status, its last crawl and the reason when it's left out.
What it doesn't do: Being indexed doesn't mean ranking. It only means the page can appear.
Updated
How it shows up in RankUpside
Each week, Google's URL Inspection runs on the client's pages that had search impressions in the last 13 weeks, revenue pages first. Each page is rechecked about every 14 days, with up to 1,800 inspections a day, through the same read-only Search Console access.
Client › Indexing lists each page with its verdict, coverage state, last crawl and the date it was inspected, with pages that aren't indexed first.
A page that had impressions or brought revenue and isn't in the index becomes a Not indexed finding, with the coverage state and last crawl. Its fix reads: check the page's indexing settings and canonical, then request indexing in Search Console. When a page vanishes from results, the ranking drop card also says whether it's still in the index.
How to check it yourself
Open URL Inspection in Search Console and paste the full URL.
Read the verdict: the page is on Google, or the reason it isn't.
Open the Page indexing report to see whether the same reason affects other pages.
Common reasons a page isn't indexed
Why a page is left out of the index, and the fix
Reason
What it means
Fix
noindex tag
The page tells search engines not to index it.
Remove the tag if the page should rank.
Canonical points elsewhere
The page names another URL as the main version.
Point the canonical at the page itself, or merge the two.
Blocked by robots.txt
Google isn't allowed to crawl the URL.
Allow the path in robots.txt.
Crawled, not indexed
Google read the page and chose not to keep it.
Make the page clearly useful and distinct, and link to it from strong pages.
Duplicate without a canonical
Google sees the page as a copy of another.
Set a canonical, or merge the duplicates.
Returns an error
The page answers with a 404 or a server error.
Fix the page or redirect the URL.
RankUpside's weekly page check also reads the canonical and noindex on every page with an open fix.
Common mistakes
Requesting indexing before fixing the reason the page was left out.
Using a site: search as proof a page is or isn't indexed. URL Inspection is the reliable check.
Related term: Ranking drop
A page that falls out of the index looks like a ranking drop in the numbers, so check indexing first.
Use the URL Inspection tool in Search Console. It shows whether the URL is on Google, when it was last crawled and, if it isn't indexed, the reason.
How often does RankUpside check indexing?
The inspection runs weekly through the same read-only Search Console access. It covers pages with search impressions, revenue pages first, and rechecks each page about every two weeks. Results show in the client's Indexing tab.
Copperline Gutters got 27 clicks from named buyer searches in the last 4 weeks, up 23% from the 4 weeks before. Google hides the search terms behind 84% of all 289 search clicks. Rankings rose across the site: pages that steadily show up are up about 2.4 positions.