A responsive website is designed to provide an optimal viewing experience across a range of devices, from desktops to smartphones. It uses flexible grid layouts, images, and CSS media queries to adjust content dynamically based on the viewing environment. In practice, this means elements like text size, images, and navigation menus automatically resize or reorganize themselves for better usability. The importance of responsive design lies in its ability to enhance user experience and improve search engine rankings, accommodating the growing diversity of devices used to access the web.