“[LEDs] have the property that we can change the light that comes out of an LED very, very quickly. That change in the brightness is what we exploit in order to encode data extremely fast, so that the receiver will be a decoder, a photo detector, which will then see these changes in the light intensity in a way a human eye would not be able to detect. To a human eye, it would be simply constant light, but for a photo detector, it is a change in the intensity, and then we have algorithms that recover these changes in intensity and get back the data stream,” Haas says.