White light emitting diodes have perfect color characteristics, but they can damage the visual adaptation to low light, so it takes some time to readjust after the light source is turned off.

Red light emitting diodes are commonly used for night vision. Compared to other colors, red light does not cause excessive pupil constriction, and once the red light is turned off, the eyes do not need to readapt to darkness. In addition, red is also used as a "safe" color in monochrome photo processing because it does not damage the film being printed.

Yellow light emitting diodes have some advantages of red and white light. In addition, yellow light can also reduce eye fatigue and glare reflex caused by long-term reading.

Green light emitting diodes can also be used for night vision, especially for reading maps or charts at night. It is not easily detected by night vision equipment, but it has lower brightness compared to red light emitting diodes.

Blue light emitting diodes can be used for reading maps at night and are usually favored by military personnel because they increase the level of contrast. In addition, they can also be used as background work lights in theaters and performances.

Blue-green light emitting diodes have similar night vision advantages of green and blue light, but as color characteristics improve, some users prefer to use blue-green light.

Infrared red light is usually used together with night vision equipment because the human eye cannot see infrared light.

Ultraviolet light is usually used to identify counterfeit banknotes. In addition, some ultraviolet light emitting diodes are popular in nightclubs and parties, where they are used to make fluorescent substances emit brighter light.

The color of light is related to wavelength. The wavelength of light is measured in nanometers, which is one billionth of a meter. The light emitted by light emitting diodes is almost uniform, that is, almost all in one wavelength, emitting very pure colors.