Responsive Web Design is an approach to web design that makes web pages render well on a variety of devices and window or screen sizes. Coursera's Responsive Web Design catalogue teaches you how to design and build websites that adapt to different screen sizes, orientations, and resolutions. You'll learn about key concepts such as fluid grid layout, flexible images, and media queries, and become proficient in technologies like HTML5, CSS3, and JavaScript. With these skills, you'll be able to create user-friendly, accessible, and professional-looking websites that provide an optimal viewing and interaction experience across different devices.