Responsive design is a web development approach that ensures websites function well on various devices, such as smartphones, tablets, and desktop computers. It uses flexible layouts, images, and CSS media queries to adapt the content to different screen sizes and orientations, providing an optimal user experience. This design technique allows for seamless navigation and readability, regardless of the device being used. By prioritizing usability, responsive design helps improve engagement and accessibility, making it easier for users to interact with the website, whether they are at home or on the go.