Responsive web design (RWD) is a web design approach aimed at crafting sites to present an optimal viewing experience, easy reading and navigation with a minimum of resizing, panning, and scrolling across a wide range of devices ranging from mobile phones, tablets to desktop computer monitors. A site designed with responsive website design adapts the layout to the viewing environment by using fluid, proportion-based grids, flexible images and CSS3 media queries, an extension of the media rule.