背光是一种被用于LCD显示上的照明形式。背光式和前光式不同之处在于背光是从侧边或是背后照射，而前光顾名思义则从前方照射。其用途为增加在低光源环境中的照明度和电脑显示器、液晶屏幕上的亮度，以和CRT显示类似的方式来产生光。

其光源可能是白炽灯泡、电光皮肤(ELP)、发光二极管(LED)、冷阴极荧光灯管(CCFL)等。电光皮肤提供整个表面均匀的光，而其他的背光模块则使用散光器从不均匀的光源中来提供均匀的光线。

背光可以是任何一种颜色，单色液晶通常有黄、绿、蓝、白等背光。而彩色显示采用白色背光，因其涵盖最多色光。

A backlight is a form of illumination used in liquid crystal displays (LCDs). As LCDs do not produce light by themselves (unlike for example Cathode ray tube (CRT) displays), they need illumination (ambient light or a special light source) to produce a visible image. Backlights illuminate the LCD from the side or back of the display panel, unlike frontlights, which are placed in front of the LCD. Backlights are used in small displays to increase readability in low light conditions such as in wristwatches, and are used in smart phones, computer displays and LCD televisions to produce light in a manner similar to a CRT display. A review of some early backlighting schemes for LCDs is given in a report Engineering and Technology History by Peter J. Wild under its section Backlit LCDs.