Basic Character LCD Hookup Guide
MikeGrusin
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How Does an LCD Work?
LCD stands for Liquid Crystal Display. These displays contain a grid of liquid crystal dots, or pixels held between layers of glass etched with transparent electrodes. Liquid crystal molecules are normally twisted, but straighten out when electricity is applied to them. This affects the way light passes through the dot, allowing it to appear either darkened or clear. A HD44780 controller chip built into the display (it's underneath the black blob on the back) receives commands from your a microcontroller, and turns the pixels on and off to form various letters, numbers and symbols. The controller datasheet has a diagram of all the characters stored in the chip. This display also has an LED for backlighting, which is powered usually through a basic character LCD pins 15 and 16.
If you look closely at the characters on the LCD, you will notice that they are actually made up of lots of little squares. These little squares are called pixels. The size of displays is often represented in pixels. Pixels make up a character space, which is the number of pixels in which a character can exist.
For more information on the history of LCDs and how they work, check out this video below.