Google’s approach of using the mobile version of a page’s content for indexing and ranking.
A practical example
A responsive service page gives mobile users the same essential copy, structured data and navigation as desktop users.
What to watch for
It does not mean mobile-only content or an automatic preference for a mobile URL. Do not hide essential information from the mobile experience.
Related reading
Explore Mobile-Friendly Website and Technical SEO. Try our noindex checker for a practical next step. See how this fits into Technical SEO.