LCDs produce images by using liquid crystals to either transmit or block light. Liquid crystals used in displays must have their molecules arrange in an orderly fashion at room temperature and also react sensitively to voltage, changing their orientation.

Liquid crystal molecules have a rod-like shape. Explained simply, when these rods are arranged horizontally, light from the bottom cannot pass through. When they are arranged vertically, however, light can pass through. The angle at which the rods are arranged defines the level of brightness in between. Using voltage to control the way these rods are arranged is the basic principle behind LCDs.