Responsive Design
A design approach that keeps visual and functional consistency across devices and screen sizes of different proportions.
In practice
Responsive design makes one layout adapt to screens of different sizes and shapes, from a narrow phone to a wide desktop monitor, while keeping content, function and visual identity consistent. Columns stack, images resize and navigation may collapse into a menu. A news site that shows three columns on a laptop and a single scrolling column on a phone, with the same stories and style, is responsive.
Often confused with adaptive design
Responsive layouts adjust fluidly to any width; adaptive design usually switches between a few fixed layouts made for specific screen sizes.
Try this
Open a website and slowly narrow the browser window, noting each point where the layout rearranges.