A rack mount monitor is a rugged display normally used with an industrial computer, though it can be used to display a video image from just about any video source. The rack in rack mount monitor refers to equipment racks. Equipment racks are very common in industry with defined standard widths, a width of 19 inches (48.26 cm) being most common.
An equipment rack is simply two vertical bars of steel with regularly spaced holes. The equipment, such as a rack mount monitor, has two flanges or ears that stick out from the equipment, with holes corresponding to the holes in the rack. This allows equipment such as the rack mount monitor to be safely and easily bolted into the equipment rack. The equipment rack's purpose is simply to provide a convenient location to hold all of the devices used in an application. For instance, if a computer is needed in a factory floor setting, then an equipment rack can be used to hold both the rack mount monitor and the computer.
A rack mount monitor uses very similar technology to what you may be reading this article on with your home or office computer. It also serves the same purpose: simply that of displaying the video image that is generated by the computer. A rack mount monitor differs from the technology on your desk only in that it is much more ruggedly packaged. It is typically mounted in a steel or aluminum frame that allows it to be mounted in a equipment rack.
However, in some cases, the packaging needs to be more extensive to protect the rack mount monitor from possible exposure to liquids, dust, or even air in some extreme situations. All of these details tend to follow industry standards, the most common of which are set by the National Electrical Manufacturers Association (NEMA). If, for example, you were to request a quotation for a rack mount monitor in a 19-inch rack mount NEMA 4 enclosure, the manufacturer of the rack mount monitor would know exactly what you want.
A feature that is frequently added to a rack mount monitor, but is unlikely to be on your desktop monitor, is a touch sensitive screen. This allows the user to interact with the computer program by touching the display, and in some cases, eliminates the need for a keypad or keyboard as an input device. Rack mount monitors are used everywhere now, and you have almost certainly encountered at least one. Video arcade games use rack mount monitors, and this is perhaps your most likely exposure to the technology.