Responsive web design (RWD) or responsive design is an approach to web design that aims to make web pages render well on a variety of devices and window or screen sizes from minimum to maximum display size to ensure usability and satisfaction.
A responsive design adapts the web-page layout to the viewing environment by using techniques such as fluid proportion-based grids, flexible images, and CSS3 media queries, an extension of the @media rule, in the following ways:
The fluid grid concept calls for page element sizing to be in relative units like percentages, rather than absolute units like pixels or points.
Flexible images are also sized in relative units, so as to prevent them from displaying outside their containing element.
Media queries allow the page to use different CSS style rules based on characteristics of the device the site is being displayed on, e.g. width of the rendering surface (browser window width or a physical display size).
Responsive layouts automatically adjust and adapt to any device screen size, whether it is a desktop, a laptop, a tablet, or a mobile phone.
Responsive web design became more important as users of mobile devices came to account for the majority of web site visitors. In 2015, for instance, Google announced Mobilegeddon and started to boost the page ranking of mobile-friendly sites when searching from a mobile device.
Responsive web design is an example of user interface plasticity.