The Li-Fi (Light Fidelity) is a wireless communication protocol that uses visible light as the data transmission medium, by modulating the amplitude of a light source that is then received by a photosensitive receiver system.

A Li-Fi system requires a transmitting part and a receiving part with an optical channel in between. The data to be transmitted will pass through this channel. The digital data arriving at the transmitter is encoded as an electrical signal, which is then converted into a light signal that modulates the brightness of a LED source. The photodetector will indeed capture these flickers, which are entirely imperceptible to the human eye (at a rate of 400 trillion times per second*), and convert them back into an electrical signal, which will then be decoded to recover the transmitted data.