Considering that more than 50% of all searches take place on mobile devices, Google’s practical advancement to “Mobile-First” Index is justified.
(More importantly, mobile now represents 65 percent of all digital media time, according to comScore in the US.)
Google has crawled the web from a “Desktop” point of view for more than a decade now. However, what’s different about the transition is that Google, so far, has been firm that business owners without a mobile website shouldn’t worry. If you only have desktop site, Google will continue to index your desktop site just usual. At the same time, Google is putting more emphasis on mobile version of a website.
So, what is Mobile-First Index?
Currently, Google has just desktop index. It creates signals based on Googlebot with the desktop user agent. Now, Google will crawl with their mobile Googlebot to gather mobile friendly and other signals too, but they aren’t creating a new index based on the mobile site.The Google Ranker then looks at the mobile signals collected by the mobile crawler and adjusts the rankings accordingly.
After all, Indexing affects ranking.
Keep in mind this update is currently in testing so you may not find any differences at the moment.