The LED (= light-emitting diode) is a diode which is able to emit light. The color of the emitted light is influenced by the material used. When a voltage is applied between the two layers (there is a negatively doped layer (n) and a positively doped layer(p)) in the direction of the flux, the excess electrons migrate towards the p-layer. Recombination then occurs in the junction layer, resulting in flashes of light (photons).

An important specification for a light source is the luminous flux in the unit lumen [lm]. The luminous flux describes the amount of light emitted by a light source. It is important to distinguish between the luminous flux of the LED, i.e. the chip itself, and the lamp. These specifications are usually (far) apart, since the luminous flux initially emitted by the LED chip is typically directed through lenses.

The color temperature (Kelvin [K]) of an LED can be divided into three categories. We speak of a warm white LED at a color temperature of up to approx. 3,200K/3,500K. From 3,500K to approx. 5,000K we speak of neutral white light. From 5,000K we speak of daylight white or cool white.