Video mirroring provides a duplicate of your monitor screen on on another display. This is typically limited to the same resolution (like 1024x768) and color bit depth (like "millions" of colors).
It is a feature most commonly found on Macintosh models which have an internal display and an external monitor port, or which have a video card that supports two monitors simultaneously.
Some computers which support video mirroring can also handle Video spanning. If a computer supports video mirroring, however, it does not necessarily support video spanning; typically, only Apple's higher-end computer models support spanning. In order to support video mirroring, a machine must have:
- a single graphics card which is capable of providing the same information to multiple displays, or
- two or more video cards installed in the same computer, and compatible software drivers for the cards.
In either case, the setup for video mirroring is within the Monitors control panel under the "Apple Menu" in "Mac OS classic" or within the Displays panel under the System Preferences application in Mac OS X.