On April 21st, Google announced that searches from mobile devices will now get results that favor mobile websites. 

"We’re boosting the ranking of mobile-friendly pages on mobile search results. Now searchers can more easily find high-quality and relevant results where text is readable without tapping or zooming, tap targets are spaced appropriately, and the page avoids unplayable content or horizontal scrolling."
http://googlewebmastercentral.blogspot.com/2015/04/rolling-out-mobile-friendly-update.html


What does this effect me?
First thing to do is examine your website with Google Mobile-Friendly Test - https://www.google.com/webmasters/tools/mobile-friendly/. If your website hasn't already been updated to Responsive Design then you're going to get a poor score. You'll also want to look and see how this has effected your page ranking in Google. 


What is Responsive/Mobile Ready Design?

A Responsive website adjusts to fit the users screen size from desktop, to tablet, to smart phone. If you shrink the size of your browser window you'll see the width decrease, the images shrink, and the content that was organized horizontally will start stacking vertically.