Luminance refers to the measure of the intensity of light that is emitted or reflected from a surface in a specific direction. It is quantified as the amount of light that is emitted per unit area of the surface, and it is typically measured in units such as candelas per square meter (cd/m²). Luminance is an important concept in fields such as lighting design, photography, and vision science, as it helps to describe how bright a surface will appear to an observer. It takes into account not only the amount of light emitted but also the angle at which the light is viewed, making it a directional property. This characteristic is crucial for understanding how light interacts with surfaces and how it is perceived by the human eye.