Unlike LED's, Vacuum Fluorescent, Plasma displays, or CRTs, Liquid Crystal Displays do not emit light. They modulate or control the movement of light. At the heart of the LCD is an ANISOTROPIC liquid crystal fluid whose molecules form distinct planes between two plates of glass. On any given plane (or level), the rod shaped molecules alogn themselves so they are all pointing in the same direction - like cigars in a box. The glass substrates used to make LCD's are coated with a POLYIMIDE layer that causes the molecules in the two outermost planes of fluid to lie at a 90º angle from each other; in other words, the individual LC molecules align themselves with this layer.