The document discusses responsive web design, which involves creating experiences that adapt to different environments and people. It notes that responsive design originated in architecture and is spreading to other fields like product design. The key idea is that a website should provide a singular experience that responds to different screen sizes, like desktops, tablets, and phones. Currently, many sites are designed for older desktop resolutions, but screens are increasingly diverse. Responsive design helps sites work well on all device types from small phones to large desktop monitors.