• Responsive websites reposition their content automatically to fit the screen size.
• If you’re viewing a website on a large monitor, things stretch out to fill the space.
• When you view the site on a smaller device, like a phone or tablet computer, the content shifts to fit.
• Google is rewarding responsive websites designed to be viewed on mobile devices (as well as laptops and monitors) with higher search result scores.

Recently Google announced changes to their search engine ranking algorithm:

“Starting April 21 [2015], we will be expanding our use of mobile-friendliness as a ranking signal. This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results. Consequently, users will find it easier to get relevant, high quality search results that are optimized for their devices.”

This means mobile-friendly responsive websites will score higher in Google results than non-responsive designs.