Seven-segment display
Overview
 
A seven-segment display (SSD), or seven-segment indicator, is a form of electronic display device
Display device
A display device is an output device for presentation of information in visual or tactile form...

 for displaying decimal
Decimal
The decimal numeral system has ten as its base. It is the numerical base most widely used by modern civilizations....

 numerals
Numeral system
A numeral system is a writing system for expressing numbers, that is a mathematical notation for representing numbers of a given set, using graphemes or symbols in a consistent manner....

 that is an alternative to the more complex dot-matrix displays. Seven-segment displays are widely used in digital clock
Digital clock
A digital clock is a type of clock that displays the time digitally, i.e. in cyphers, as opposed to an analog clock, where the time is displayed by hands. Digital clocks are often associated with electronic drives, but the "digital" description refers only to the display, not to the drive mechanism...

s, electronic meters, and other electronic devices for displaying numerical information.

The idea of the seven-segment display is quite old. In 1910, for example, a seven-segment display illuminated by incandescent bulbs was used on a power-plant boiler room signal panel.
A seven segment display, as its name indicates, is composed of seven elements.
 
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