Google has been indicating that they were going to increase their focus on mobile users. They sent out notifications to website owners who needed to fix mobile usability issues, they launched a mobile-friendly testing tool, and they began including mobile-friendly labels in their search results. This led many in the SEO community to speculate that Google would soon be updating its search algorithm to include mobile usability.
This was confirmed by Google on February 26, 2015; in a blog post, they stated that beginning April 21, mobile-friendliness would be a ranking signal, and that it would have a significant impact on search results, affecting mobile searches in all languages worldwide. This means that sites which are not mobile-friendly will receive a penalty in search results, and likewise, sites which are configured to provide a good experience for mobile users will rank higher.
In addition, Google has begun using App Indexing (starting immediately) to include information from Android apps in search results. This will affect mobile users using an Android phone who have an indexed app installed.
How Does this Affect me?
As more and more people use mobile devices to access websites, making sure that they are able to use the full functionality of the website no matter what device or screen size they are using is becoming more and more important. It’s obvious that Google recognizes this, and with this update, mobile usability can now make the difference in whether people are able to find your site online.
Source: Wsol