A lumen is a unit of measurement used to measure the total amount of visible light emitted by a source. It is most commonly used when referring to the brightness of an electric light, however it can also be used to quantify other forms of visible light such as sunlight or starlight. A single candle produces approximately 1 lumen, while a 100 watt incandescent bulb will produce about 1600 lumens.
Lumen
