Luminance is a concept that describes how bright a display device is. The brighter the screen is, the more clearly the image or video on the screen can be seen even under the sunlight outdoors. As a result, luminance is used as an important indicator of display performance. The unit is cd/㎡ (candela) or nit, and 1 candela is equal to the brightness of a single candle. Luminance refers to the degree to which light is emitted from a light source or the amount indicating the brightness of a secondary light source that emits and is reflected from a surface. For displays, luminance is an indicator of the device’s brightness, and its unit is expressed in cd/m2 (candela) or nit. For example, 1 cd/m2 (=1nit) is equivalent to lighting a single candlelight per square meter. A display with high luminance offers clear screen visibility even outdoors. Moreover, luminance is an important indicator for displays because it is conducive to bringing about the HDR effect.