Mobile-First Indexing
Mobile-first indexing means that Google predominantly uses the mobile version of a website's content for indexing and assessment, even for queries made on the desktop – a change Google completed for practically all websites by 2023/2024.
In practice
Content, structured data and links must be present on the mobile version in full and on a par with the desktop version. A mobile page with less content than the desktop variant can have a directly negative effect on rankings. In practice, it is worth comparing both views regularly, particularly after larger website updates.