Starting April 21, 2015, Google's mobile search algorithm is changing to emphasize web sites that are mobile-friendly. What does this mean for your website? If your site isn't optimized and easy to use for mobile users, it will likely get less traffic and go down in the search rankings when people use their mobile devices. Read more about this on Entrepreneur.com.
A site is mobile-friendly if it's fast loading, features readable text without zooming, properly sizes content and photos so the user doesn't have to scroll sideways, and has links that are easy to click.
Check out this mobile friendly test to see if you're ready!