Dual-monitor

Multi-monitor, also called multi-display and multi-head, is the use of multiple physical display devices, such as monitors, televisions, and projectors, in order to increase the area available for computer programs running on a single computer system. Research studies show that, depending on the type of work, multi-head may increase the productivity by up to 50-70%.

Multiple computers can be connected to provide a single display, e.g. over Gigabit Ethernet/Ethernet to drive a large video wall.

One way to extend the number of displays on one computer is to add displays via USB. Starting in 2006, DisplayLink released several chips for USB support on VGA/DVI/LVDS and other interfaces.

In many professions, including graphic design, architecture, communications, accounting, engineering and video editing, the idea of two or more monitors being driven from one machine is not a new one. While in the past, it has meant multiple graphics adapters and specialized software, it was common for engineers to have at least two, if not more, displays to enhance productivity.

Multi-monitor gaming/simulation is also becoming more common; however, the hardware expense can be a limiting factor. The rising popularity of using multiple monitors to game is leading to websites being introduced which allow for smooth and easy configuration from outside sources from the original one screen option given by developers to a new multiple screen option.

Early versions of DOOM permitted a three-monitor display mode, using three networked machines to show left, right, and center views.

More recently, games have used multiple monitors to show a more absorbing interface to the player or to display game information. Various flight simulators can use these monitor setups to create an artificial cockpit with more realistic interfaces. Others such as Supreme Commander and World in Conflict can use an additional monitor for a large scale map of the battlefield.

...
Wikipedia