Computer monitor
![The area, height and width of displays with identical diagonal measurements vary dependent on aspect ratio.](/Images/godic/202501/09/Screens_png2011.png")
![A fixed 19-inch (48 cm), 4:3 rack mount LCD monitor](/Images/godic/202501/09/Rackmount-LCD2011.jpg")
![A 1U stowable clamshell 19-inch (48 cm), 4:3 rack mount LCD monitor with keyboard](/Images/godic/202501/09/Rackmount-KVM2011.jpg")
![A panel mount 19-inch (48 cm), 4:3 rack mount LCD monitor](/Images/godic/202501/09/Panel-Mount-LCD2011.jpg")
A computer monitor or a computer display is an electronic visual display for computers. A monitor usually comprises the display device, circuitry, casing, and power supply. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) or a flat panel LED display, while older monitors used a cathode ray tubes (CRT). It can be connected to the computer via VGA, DVI, HDMI, DisplayPort, Thunderbolt, LVDS (Low-voltage differential signaling) or other proprietary connectors and signals.