LED stands for "Light Emitting Diode"; also called "luminescent diode". It is an electronic semi-conductor device. When forward current flows through the diode, it emits light, infrared radiation or even ultraviolet radiation at a wavelength that depends on the semi-conductor material.
In conventional incandescent bulbs current is first converted to heat. This results in significant energy loss. About 95 % of the total input energy is wasted in this way. By contrast, light emitting diodes convert current directly into light.
In this way LED lights only consume a fraction of the power that would be needed if illuminating conventional bulbs. And yet the brightness of LED lamps is comparable to and frequently better than that of conventional bulbs, the majority of which use ten times as much power with the associated running costs.
You can have LEDs in many shapes and types, for example, as candles, bulbs, tubes, spotlights or even light emitting floodlights. In addition, they can be found in all RGB colours and in different tones of white, such as warm white or neutral white.