TFT flattens CRT

The flat display reduces the huge backspace needed for crt monitors. The important ingredient is TFT (Thin Film Transistors), a tiny transistor arranged on a glass substrate like a matrix. During displaying to light up a particular pixel, Firstly the row and column were switched on then a charge is sent so that only the capacitor at that pixel receives a charge. This capacitor holds the charge until next refresh cycle.
The amount of voltage supplied allows only some light to pass through. By this process LCDs can create a gray scale to show color, for colors LCD must have three subpixels with red, green and blue filters. By control of the voltage, the intensity of each subpixel can be varied over 256 shades. Combining all the subpixels gives 6.8 million colors.