Google announced one year ago that it would start mobile-first indexing, with the effort beginning in March. The company today shared that this method for improving mobile Search results is now used for “over half of the pages shown in search results globally.”
The Googlebot responsible for crawling, indexing, and ranking has long analyzed the desktop version of a page. However, this is not representative of web and Search usage today given that the full site might be “vastly different” from the mobile version in terms of content.
Since the company began experimenting with mobile-first indexing two years ago, Google notes that more sites have embraced the mobile web. Sites are moved to mobile-first indexing by the “Googlebot Smartphone” when tests show that a page is ready, namely it features a responsive design.
When we move sites over, we notify the site owner through a message in Search Console. It’s possible to confirm this by checking the server logs, where a majority of the requests should be from Googlebot Smartphone. Even easier, the URL inspection tool allows a site owner to check how a URL from the site (it’s usually enough to check the homepage) was last crawled and indexed.
Google advises developers to make sure mobile pages carryover structured data from the desktop counterpart. It also notes how a “page does not need to be mobile-friendly in order to be considered for mobile-first indexing.”
If you use structured data on the desktop versions of your pages, you should have the same structured data on the mobile versions of the pages. This is important because with mobile-first indexing, we’ll only use the mobile version of your page for indexing, and will otherwise miss the structured data.
Meanwhile, another improvement Google notes is missing alt-text for images on mobile pages.
Check “img” tags in the source code of the mobile version for representative pages of your website. As above, the source of the mobile version can be seen by either using the browser to simulate a mobile device, or by using the Mobile-Friendly test to check the Googlebot rendered version. Search the source code for “img” tags, and double-check that your page is providing appropriate alt-attributes for any that you want to have findable in Google Images.