First, the backlight shoots light through a thin layer of liquid crystals. As the light passes through it's reflected at different angles by the crystals' orientation.

The angle of reflection determines the color of the light we see. In order to change the angle (and by extension, color) the display hardware must apply a voltage across the liquid crystals to change their orientation.

In order to produce a wide range of colors, each pixel is broken down into three subpixels: red, green, and blue.

Separate voltages are used to adjust the intensity of each subpixel which, when combined, can create millions of different colors.