Liquid crystal display (LCD)

An LCD screen used as a notification panel for travellers
Liquid crystal displays (LCDs) are lightweight, compact, portable, cheap, more reliable, and easier on the eyes than cathode ray tube screens. LCD screens use a thin layer of liquid crystal, a liquid that exhibits crystalline properties. It is sandwiched between two electrically conducting plates. The top plate has transparent electrodes deposited on it, and the back plate is illuminated so that the viewer can see the images on the screen. By applying controlled electrical signals across the plates, various segments of the liquid crystal can be activated, causing changes in their light diffusing or polarizing properties. These segments can either transmit or block light. An image is produced by passing light through selected segments of the liquid crystal to the viewer. They are used in various electronics like watches, calculators, and notebook computers.

LCD with backlit light-emitting diode (LED)
Some LCD screens are backlit with a number of light-emitting diodes (LEDs). LEDs are two-lead semiconductor light sources. The image is still generated by the LCD. LED-backlit LCD displays are the most prevalent in the 2010s.