There are two ways to backlight an LCD display: using electro-luminescent foils, and using Cold-Cathode Fluorescent Tubes

Today's LCD displays are magnificent devices: thin, bright display, wide viewing angle, light, low power consumption, high resolution. There's one drawback, however: after several years of extensive use, the backlight wears out and eventually dies. "Several years" is really really a short lifetime compared to cathode based monitors (you know, the heavy power hungry thing sitting on your desk). The basic components of a backlight display are a device to produce a high voltage, called an "inverter", and the CCFT tube itself. If your backlight is broken, then there are two possible causes: (1) your inverter broke down or (2) your tube has worn out. It is usually located in the LCD screen itself, because the wires to the CCFT tube should not be too long, and carry a high voltage. So they should be confined inside the display casing to minimize the risk of wire exposure.