Mobile-First Indexing
Google's practice of using the mobile version of a page as the primary basis for indexing and ranking, rather than the desktop version. Because most searches happen on phones, the content, links, and structured data present on your mobile site are what determine how you rank for everyone.
Why It Matters
If your mobile version hides content, links, or metadata that exists on desktop, those signals effectively disappear from ranking consideration. Mobile-first indexing makes full parity between mobile and desktop essential to preserving visibility.
Common Mistake
Serving stripped-down mobile pages that omit body content, structured data, or internal links present on desktop. Blocking mobile resources like CSS and JavaScript also prevents proper rendering and evaluation.