Dot-matrix display
A dot-matrix display is a low-cost electronic digital display device that displays information on machines such as clocks, watches, calculators, and many other devices requiring a simple alphanumeric (and/or graphic) display device of limited resolution. The display consists of a dot matrix of lights or mechanical indicators arranged in a rectangular configuration (other shapes are also possible, although not common) such that by switching on or off selected dots, text or graphics can be displayed.