Google announced in a blog post just before Christmas that over 50% of the results shown in their search results were now based on mobile-first indexing. This means over half the results you see are based on Google crawling and indexing the mobile rather than the desktop version of the page.
Mobile-first indexing was rolled out more widely after testing by Google in March 2018, with sites which followed best practice being the first to be migrated.
Google says they use mobile-first indexing when sites are ready:
"In general, we move sites to mobile-first indexing when our tests assure us that they're ready."
If your site uses responsive design, you’re good to go. For sites that don’t, Google says the two problems which come up most frequently in its evaluations are:
- missing structured data on mobile pages, and
- missing alt-text for images on mobile pages.
Google notifies site owners when their sites are moved across via a message in Search Console.
You can also use the URL inspection tool to check how a URL from your site was last crawled and indexed.
Image source: Google
With over half of Google’s results now powered by mobile first indexing, if you haven’t yet tackled this issue, it’s time to do so. A difference in content and structured data between the desktop and mobile versions of your pages may affect your rankings.
For help getting your site ready for mobile, see Google's advice and resource page:
https://developers.google.com/search/mobile-sites/mobile-first-indexing
