Computer screens these days are almost always LCDs with an LED backlight (sometimes mistakenly called an “LED display,” which it isn’t). The major components of an LCD are:
Two very thin sheets of glass. On one of these, a thin film of silicon has been deposited and used to make a very large number of tiny transistors, each of which controls one subpixel (red, green, or blue) of the display. There will also typically be a number of small integrated circuits mounted near the edges of this sheet, which are the drivers for the rows and columns of the display.
The other sheet of glass carries electrodes made of a very thin, transparent film of indium-tin-oxide (ITO) and an array of color filters (red, green, and blue), three for each pixel, and separated by a black surround material. These are typically made using a photographic process and are made from a special resin called photoresist.
On both sheets of glass, a polarizing film is added; the polarization directions of these two films are typically at right angles to one another so that if nothing else happens, little or no light would pass through the two. (The liquid crystal material, under the control of the transistors on the glass, can change the polarization of light and so can switch each subpixel on and off.)
Between the two sheets is a very thin layer, perhaps 5–10 microns in thickness, of a liquid, which is the liquid crystal itself. This is an organic material with a specific molecular structure which permits the LCD to operate as described above.
“Behind” the glass sheets, as seen from the front of the display, are a series of plastic sheets and films which form the backlight. These are used to make the backlighting appear uniform and to direct the light toward the front of the display. The light itself is generated by a strip of LEDs mounted to the edge of this assembly.
The whole stack as described above will be contained within a sheet metal frame, which provides mechanical strength to the assembly and also will carry the mounting hardware and connectors. A small printed circuit board will also be included which carries the control electronics for the panel.