What does a lumen measure?

A lumen is a unit of measurement that quantifies the amount of visible light emitted by a source in a specific direction. It is a standard measure used to describe the light output of bulbs and other lighting devices. The higher the lumen rating, the more light the source produces. This measurement is essential for consumers to understand the brightness they can expect from different light sources, influencing their choices when selecting lighting for their spaces.

The other options do not accurately represent what a lumen measures. For example, volume of light does not correspond to a recognized measurement in optics; instead, lumens focus on light output. Similarly, intensity of darkness and distance of light are not relevant to the measurement of lumens, as they pertain to different aspects of light and vision, rather than the quantitative output of light itself.