Big news yesterday, but we saw it coming, was that Google announced all sites are going to be moved over to mobile-first indexing by September 2020. Google is sending out notices about this, Google started doing that last week. But Google also said that 70% of the sites served in search already are through mobile-first indexing.
So Google only has to move over 30% of the remainder of those sites in the index (well, probably a bigger number than 30% if you count by what is in Google's index versus what Google serves to searchers).
So this effort will have taken Google about four-years to move from a desktop-first indexing process to a mobile-first indexing process. What that means, if this is new to you, is Google will crawl and index your site based on the way a mobile phone (i.e. Chrome on Android) looks at your web site.
The remaining 30% are those sites that look so differently; in terms of content, structured data, links, images, etc when comparing the desktop and mobile site - that Google feels it is a bit dangerous to move the site. Dangerous in that it will drop in rankings if moved.
So Google is notifying webmasters of the issues they need to address by September so the site can move over to mobile-first indexing. If you do nothing, then the rankings will probably shift for the site.
Google has a lot more detail over here.
One question I saw Google answer on this, but it should be obvious I guess, is that this is a global rollout and global change:
Mobile-First Indexing at Google is becoming the default later this year. Googlebot is leaving its desktop behind, and using a phone, like most of our users. Curious to find out more? Check out our blog post! https://t.co/yfrpwLc4mX
— Google Webmasters (@googlewmc) March 5, 2020
Yes
— 🍌 John 🍌 (@JohnMu) March 5, 2020
You can check in Search Console if your sites were moved over yet - more on how over here.
Forum discussion at Twitter and WebmasterWorld.
