Here is a good one-liner from Google's John Mueller on the technicalities of the Google index. John said on Twitter "A page's content doesn't need to be indexed for a page to be indexed."
John added this also applies for hreflang pairs to be used, he said "or for it to be used with hreflang pairs if they're equivalent." "That's perfectly fine, and not a sign of an issue," he added.
Here are those tweets:
I'm not really sure what you're asking... A page's content doesn't need to be indexed for a page to be indexed, or for it to be used with hreflang pairs if they're equivalent. That's perfectly fine, and not a sign of an issue.
— John Mueller is mostly not here 🐀 (@JohnMu) November 29, 2022
One example is a page that's disallowed from crawling by robots.txt. Another is when a page is known as a part of a hreflang set and the URL is swapped out. Or when you search for an old URL that's been redirected.
— John Mueller is mostly not here 🐀 (@JohnMu) November 29, 2022
What does this mean? Technically, Google does not have to index the content, these words, the HTML, the images, etc on this page fo the page to be in Google's index. Google can just process the URL of this page, and the URL that this page exists and may or may not have content or HTML on it may be indexed. So URLs that pages exist can be in Google's index, with or without the content.
Ultimately, you want your content indexed, so Google can really judge if that page in Google's index should be ranked for your desired query. But this is just a technicality, in terms of how John is referencing this and I love it.
Forum discussion at Twitter.
