A responsive website (sometimes referred as Mobile adaptive website) is one that responds (or changes) based on the needs of the users and their device. For instance, text and images change from a three-column to a single column display layout, unnecessary images are hidden so they don’t interfere with the more important data on the smaller display.
Responsive design offers flexibility and great usability on all devices for users. The website automatically changes itself based on the screen size of the device
Key features of responsive websites: Dynamic content that changes, navigation is condensed, optimized images, correct padding and spacing, reliant on mobile operating systems to function.
In addition, Mobile responsive and mobile adaptive sites are similar (sometimes mistaken as the same thing), but different in practice. They both change dimensions based on the browser and device. Responsive sites adjust to any layout while adaptive sites only adapt at select points. Adaptive is easier and significantly cheaper to deploy since the images are scaled down, rather than resized.