Optical communication is any form of telecommunication

Telecommunication

Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

 that uses light

Light

Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

 as the transmission medium

Transmission medium

A transmission medium is a material substance that can propagate energy waves...

.

An optical communication system consists of a transmitter

Transmitter

In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...

, which encodes a message into an optical signal, a channel

Channel (communications)

In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel...

, which carries the signal to its destination, and a receiver, which reproduces the message from the received optical signal.
There are many forms of non-technological optical communication, including body language

Body language

Body language is a form of non-verbal communication, which consists of body posture, gestures, facial expressions, and eye movements. Humans send and interpret such signals almost entirely subconsciously....

 and sign language

Sign language

A sign language is a language which, instead of acoustically conveyed sound patterns, uses visually transmitted sign patterns to convey meaning—simultaneously combining hand shapes, orientation and movement of the hands, arms or body, and facial expressions to fluidly express a speaker's...

.

Techniques such as semaphore lines, ship flags, smoke signals, and beacon fires

Beacon

A beacon is an intentionally conspicuous device designed to attract attention to a specific location.Beacons can also be combined with semaphoric or other indicators to provide important information, such as the status of an airport, by the colour and rotational pattern of its airport beacon, or of...

 were the earliest form of technological optical communication.

The heliograph

Heliograph

A heliograph is a wireless solar telegraph that signals by flashes of sunlight reflected by a mirror. The flashes are produced by momentarily pivoting the mirror, or by interrupting the beam with a shutter...

 uses a mirror

Mirror

A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...

 to reflect

Reflection (physics)

Reflection is the change in direction of a wavefront at an interface between two differentmedia so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves...

 sunlight to a distant observer.