The technology that uses responsive designs for optimal viewing is typically called web design or responsive web design (RWD). This approach ensures that web pages adapt seamlessly to various screen sizes and devices, such as desktops, tablets, and smartphones. By employing flexible grids, layouts, and media queries, responsive web designs provide users with an enhanced browsing experience, regardless of the device. This adaptability is crucial in today's mobile-centric world, where users expect functionality and aesthetics to be maintained across platforms.