Today, we see a sharp rise in the interest in communicating wirelessly over an optical channel, for instance, building networks that are free from adjacent cell interference. LEDs are already widely used in illumination, and LED LiFi systems that carry up to gigabits per second are commercially available. Progress in wireless communication relies, to a significant extent, on a solid understanding of the channel properties. However, the LED channel distinctly differs from the RF channel. In this overview, we explore the peculiarities of the LED channel and discuss the consequences for the design of the communication system.