Digital Visual Interface or Digital Video Interface, better known as DVI, is a video interface standard. It was established by the Digital Display Working Group (DDWG) to maximize resolution of digital flat panel displays. Visual Graphics Array (VGA), the standard previous to DVI, is an analog technology that was designed for cathode ray tube (CRT) monitors.
Why the switch to DVI? Graphics cards generate digital signals that then pass through a Random Access Memory Digital to Analog Converter (RAMDAC), where they are converted to analog signals to accommodate CRT monitors. The conversion from digital to analog "slurs" the signal in minute ways that result in a picture that isn't as sharp as it should be or would be if purely digital. This explains why, as analog CRT monitors became larger and resolution greater, text was not as sharp as it should have been and very small fonts became blurry. A natural progression was to make an industry switch to digital displays with digital interfaces.
DVI eliminates the unneeded analog interpreter from translating digital signals between digital components. Digital flat panel displays use a method whereby each pixel is mapped to a numerical value that establishes its level of brightness each time the frame is painted, which occurs many times per second. Inherently this is more exacting than CRT technology. When the analog conversion is eliminated, the result is optimal. If the digit "1" is relayed, the receiver will get "1" and nothing else. If sent via analog, the "1" might look more like .0952 or 1.002.
Intel, IBM, NEC, Compaq, Fujitsu, Hewlett Packard and Silicon Image formed the DDWG consortium that developed DVI. The market transitioned from the old VGA standard to the DVI standard with many flat panel displays and graphics cards featuring both VGA and DVI interfaces to accommodate intermixed components. There are several types of DVI cable formats for varying hardware standards. DVI has since been superseded by two newer digital standards: Unified Display Interface (UDI), and DisplayPort.