Responsive web design (RWD) creates dynamic changes to a website's appearance depending on the viewing device's screen size and orientation. The presentation discusses how RWD works using media queries to rearrange and resize website elements like images, text containers, and sidebars for different devices. It provides examples of redesigning elements like search pages, timelines, and video pop-ups to work well across desktop, tablet, and phone screen sizes and orientations. The presentation recommends starting with a responsive framework like Bootstrap or Foundation to simplify the process of building responsive websites.