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Light-emitting diode

A light-emitting diode (LED) is a semiconductor device that emits light when an electric current passes through it.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

A light-emitting diode (LED) is a semiconductor device that emits light when an electric current passes through it. LEDs are used in indicator lights, displays, and general lighting because they are efficient, durable, and available in different colours.

Operation

LEDs produce light through electroluminescence when electrical current passes through a semiconductor junction. The colour of the emitted light is determined by the semiconductor material's band gap.

Applications

LEDs are used in a wide range of applications including device indicators, digital and alphanumeric displays, home and commercial lighting, traffic signals, remote controls, automotive lighting, and optical communications.

Advantages

Compared to incandescent lighting, LEDs typically consume less power, last longer, and produce less waste heat. Their directional output also makes them well-suited for many lighting and display systems.

History and development

LEDs were initially used in simple indicator and display roles. As materials and manufacturing processes improved, their use expanded into general lighting and specialized optical applications.

Key facts

  • LED stands for light-emitting diode.
  • An LED is a semiconductor diode that produces light when current flows through it.
  • The light output can be visible or infrared.
  • LEDs are widely used in indicator lamps, electronic displays, and lighting.
  • They are known for low power consumption and long service life.
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Canadian context

LEDs are widely used across Canada in household lighting, vehicles, road signage, electronics, and telecommunications, where energy efficiency and cold-weather durability are practical advantages.

Frequently asked questions

What does LED stand for?
LED stands for light-emitting diode.
How does an LED produce light?
An LED produces light when electric current passes through a semiconductor, releasing energy as photons.
What are LEDs used for?
LEDs are used in indicator lights, digital displays, lighting, traffic signals, remote controls, and fibre-optic systems.
Why are LEDs popular?
They are popular because they are energy-efficient, long-lasting, and can be made in many colours.
Do LEDs produce visible and infrared light?
Yes. LEDs can be designed to emit visible light or infrared light.

References

  1. Encyclopaedia Britannica — https://www.britannica.com/technology/LED
    Supports: Definition of LED as a semiconductor device that emits infrared or visible light when charged with electric current.
  2. Encyclopaedia Britannica — https://www.britannica.com/summary/LED
    Supports: Uses in indicator lamps, displays, optoelectronics, and fibre-optic communications; low power and long life.
  3. Wikipedia — https://en.wikipedia.org/wiki/Light-emitting_diode
    Supports: Basic operation, electroluminescence, semiconductor recombination, and colour dependence on band gap.
  4. ENERGY STAR — https://www.energystar.gov/products/learn-about-led-lighting
    Supports: Energy efficiency, directional light output, and general LED lighting operation.
  5. IUPAC — https://www.iupac.org/materialschemistryedu/computing/leds/
    Supports: Basic description of LEDs as semiconductors that produce light when current passes through them.