Responsive web design is a strategy to ensure web pages work well across various screen sizes and devices. It allows content to be fluid and adapt based on the dimensions of the user's screen. Effective responsive design incorporates techniques like media queries and flexible images. This adaptability improves the overall user experience, as content remains accessible and aesthetically pleasing on all devices. Furthermore, responsiveness enhances SEO, as search engines prioritize mobile-friendly websites. Adopting responsive design is crucial in modern web development for reaching a wider audience.