Google crawls and indexes your website based on the experience, quality, and content on your website. The index prioritizes websites based on the experience and if it is related to the query.
With Google's new mobile-first index, they will look at your mobile content first and then index your site based on that. That is why this latest algorithm changes is called mobile-first indexing. Google has confirmed that overall rankings should not change very much. You can use the mobile index as an opportunity to improve your mobile user experience which can ultimately improve your desktop performance as well since your site will likely improve in ranking.
Why did Google decide to make this mobile-first change?
Google recognizes that more and more people are using mobile for online searches. In fact, people are using mobile more than computers when they do Google searches. Since mobile is the most popular way to search for information on Google, it is only fair that mobile rankings should be taken into account with the overall ranking of a website. Both the mobile and desktop experiences are essential. Google is using this indexing as a means to keep businesses responsible when it comes to the user experience and functionality of mobile sites. Mobile sites would have to be a focus now if they were not before.
How can you improve your mobile site?
First, make sure that your website is mobile friendly. Users should be able to see the same data from the desktop version in the mobile version of your site. Make sure the user experience and content are consistent across both platforms. If you haven't already, consider implementing responsive design for your website so that it performs well no matter the screen size.
Make sure that all the content on your mobile site is easy to access and that your mobile site speed (page load time) is fast. Google has a free tool available so you can test your mobile site. We're also happy to take a look if you'd like advice on areas to improve.