A display device is an output device for presentation of information in visual or tactile form (the latter used for example in tactile electronic displays for blind people). When the input information that is supplied has an electrical signal, the display is called an electronic display.
Common applications for electronic visual displays are televisions or computer monitors.
In the history of display technology, a variety of display devices and technologies have been used.
Some displays can show only digits or alphanumeric characters. They are called segment displays, because they are composed of several segments that switch on and off to give appearance of desired glyph. The segments are usually single LEDs or liquid crystals. They are mostly used in digital watches and pocket calculators. There are several types:
Seven-segment display (most common, digits only)
HD44780 LCD controller a widely accepted protocol for LCDs.