Mobile-first indexing
Mobile-first indexing means Google reads and ranks the mobile version of your pages, so what's missing on a phone is missing for Google.
Mobile-first indexing means Google uses the mobile version of your site to index and rank it. Its crawler visits as a smartphone, and what it finds there is what counts. If a page shows less on a phone than on a laptop, the extra text on the laptop version may as well not exist for Google.
Google finished moving the web over to it years ago. Its mobile-first indexing guide lists what to check.
What can go wrong
Most sites now use one design that adapts to the screen, so the same content shows everywhere and there's little to worry about. Problems come from sites that change what they show by device:
- Text, reviews or specifications left out of the mobile layout to save space
- Content that only loads when someone taps or scrolls on a phone
- Different headings, titles or structured data on the mobile version
- Images on mobile with no alt text, or in a format Google can't read
- A separate mobile site that robots.txt blocks by mistake
For example, Harrow & Pine's product pages show a full table of dimensions and materials on desktop, but hide it on phones to keep the page short. Google reads the phone version, so when someone searches "oak sideboard 180cm," the page has nothing that says 180cm.
What it means for AI search
AI platforms' bots aren't Google's crawler and don't all read pages the same way. But the lesson carries over: a bot reads what the server sends it, and text that's hidden, cut or added later by a script may never reach it. Google's own AI features are built on its index, so what mobile-first indexing misses, they miss too.
In AnswerOrbit
The Pages tab in Website shows each page side by side, as a person sees it and as a bot reads it, and marks the blocks bots miss. It also shows each page's health on a phone. Fast on phones is one of the eight page checks.