LEDs

An LED (light-emitting diode) is a semiconductor light source that emits light when current flows through it.

There are several different modern types including visible, UV (ultraviolet), and infrared LEDs.

Visible LEDs include single, double and multiple colors and intensities. UV LEDs  produce specific narrow ranges of UV wavelengths that are commonly used for sanitizing and sterilization purposes. Lastly infrared LEDs produce light in the infrared band of the electromagnetic radiation spectrum. They are commonly used security sensors/cameras and remote controls.