DVI, or Digital Visual Interface, carries an uncompressed digital video signal to a digital display device such as an LCD display or projector. The protocol delivers the signal in a digital bit stream, sending frame and line information as discrete red, green and blue color components….Many DVI graphics cards won’t output video unless there is a DVI display device attached. Most routers, switchers and projectors use EDID, or Extended Display Identification Data, to send information back to the DVI source. It tells the source device, such as a PC, to output a digital video signal at a specific resolution, and also gives the graphics card the signal that it’s okay to start sending digital video through the DVI cable.
— Vickie Claiborne, from Video Digerati, PLSN, July 2008
