An LCD screen includes a thin layer of liquid crystal material sandwiched between two electrodes on glass substrates, with two polarizers on each side. A polarizer is an optical filter that lets light waves of a specific polarization pass through while blocking light waves of other polarizations. The electrodes need to be transparent, so the most popular material is ITO (Indium Tin Oxide).
As LCD can’t emit light itself, normally a backlight is placed behind an LCD screen in order to be seen during the dark environment. The light sources for backlight can be LED (Light Emitting Diode) or CCFL (Cold Cathode Fluorescent Lamps). The LED backlight is most popular. Of course, if you like to have a color display, a layer of color filter can be made into an LCD cell. The color filter consists of RGB color. You can also add a touch panel in front of an LCD.