What is a responsive web design?

A responsive web design is characterized by its ability to adapt seamlessly to various devices and screen sizes, ensuring that content is displayed optimally regardless of whether the user is on a desktop computer, tablet, or smartphone. This adaptability is achieved through fluid grid layouts, flexible images, and CSS media queries, all of which allow the website's layout and features to adjust smoothly in response to the dimensions of the viewing device.

This approach enhances user experience by making web content accessible and easy to navigate on any platform, which is essential in today's multi-device environment. The other options describe design concepts that do not account for the variability of input devices: one restricts design to desktops, another is limited to mobile, and the last suggests a static nature, none of which embody the flexibility and user-centric focus that defines responsive web design.