Responsive web design ensures that websites look and function well on all devices, from desktops to smartphones. With mobile traffic increasing rapidly, creating a responsive site is essential for user engagement and SEO. Techniques like flexible grids, media queries, and adaptive images help developers build layouts that adjust to screen size. Using frameworks like Tailwind CSS or Bootstrap can speed up the process. Responsive design improves user experience, increases accessibility, and ensures that your site stays competitive in 2025.