Since Tuesday, Google has been sending notices around mobile-first indexing being enabled for websites to a huge number of webmasters. It seems like this batch of notices is by far the single largest batch of notices we’ve seen since they officially began sending these types of batch notifications around the mobile-first indexing change.
So if you received a notice, trust me, you are not alone.
What is mobile-first indexing? Google explained their “crawling, indexing and ranking systems have typically used the desktop version of a page’s content, which may cause issues for mobile searchers when that version is vastly different from the mobile version. Mobile-first indexing means that we’ll use the mobile version of the page for indexing and ranking, to better help our — primarily mobile — users find what they’re looking for.” In short, Google is crawling the web as a smartphone browser would render your website, as opposed to how a desktop browser would.
How does it impact my rankings? Google hopes that it won’t have an impact on your rankings. But if your site’s content is vastly different on desktop versus mobile, then it can impact your rankings on Google search. Google has historically moved sites over that show little change between mobile and desktop versions of their site (or if they just have a desktop-only version). But Google with this batch may have moved sites that have more differences between their desktop and mobile site.
Advice from Google? Google issued these clarifications a few months back with new and clearer advice around this change.