Even the earliest humans used color to direct each other’s attention and emphasize the things most important to them. Understanding what color and light actually are—in terms of physics and chemistry, but also in the eye and the mind—has always influenced what color and lights humans actually make. And vice versa. But the technology of the industrial age sparked what some historians have called a “chromatic revolution,” an era when color and light became tools not only of art but also of design, business, and marketing. That era hasn’t ended. We still use color to emphasize what’s important to us, but also to redirect what we all think is important. The story of color is the story of our shared culture.