Responsive web design (RWD) is an approach to web design aimed at crafting sites to provide an optimal viewing and interaction experience—easy reading and navigation with a minimum of resizing, panning, and scrolling—across a wide range of devices (from desktop computer monitors to mobile phones).[1][2][3]
A site designed with RWD[1][4] adapts the layout to the viewing environment by using fluid, proportion-based grids,[5][6] flexible images,[7][8][9] and CSS3 media queries,[3][10][11] an extension of the @media rule, in the following ways:[12]
The fluid grid concept calls for page element sizing to be in relative units like percentages, rather than absolute units like pixels or points.[6]
Flexible images are also sized in relative units, so as to prevent them from displaying outside their containing element.[7]
Media queries allow the page to use different CSS style rules based on characteristics of the device the site is being displayed on, most commonly the width of the browser.