Widescreen television sets and computer monitors all need video input signals to make them operate. Various digital and analog formats produce those signals with various results, and travel over different cable systems. Higher-quality formats keep information for the three primary video colors on separate signals. Formats that keep red, blue and green video signals separate include VGA, component video, DVI and HDMI.
Video graphics array was developed in 1987 by IBM to present better video on computer screens. By keeping color information separate on three analog signals, VGA succeeded in producing higher quality video, primarily for graphics applications. Although VGA technology remains in use for analog screen presentations, digital formats are increasingly being used for larger screens. VGA travels on a cable with 15-pin connectors and does not include audio. With VGA, you need separate cables for sound. Component video is similar to VGA for home entertainment systems, but travels on three coaxial cables.
Digital video interface was developed in 1999 to send the video signals from computers to their screens in a digital form, much the same way computers deliver packets of information from one to another. By converting the color information into digital pulses, the signals create clearer screen presentations. DVI travels over a single cable with various types of multi-pin connectors, some with additional pins for information applicable to specific systems. DVI does not carry any audio signals, and although primarily used for computer screens, the technology evolved into HDMI for video signals for home entertainment systems.
High-definition multimedia interface was developed in 2002 and connects various home entertainment system video sources such as DVD players, satellite or cable receivers, digital video recorders, game consoles or computers to a video screen. The interface uses a single cable to carry digital video signals for HDTV screens of the highest quality along with up to eight channels of audio over a single cable with 21-pin connectors on the ends. With an HDMI connection, you don't need separate cables for audio. The video portion of HDMI technology is the same as DVI.
A video screen displays dots to create a picture. The more dots, the clearer the picture, but the more information needed. Digital signals provide more information for dots, but analog signals make a picture softer. Larger screens need more dots for closer viewing, but from a distance this becomes moot. So the quality question revolves around technology, application and personal preference. VGA, DVI and HDMI all provide high-quality pictures. Digital presentations may be better for graphics displays for design, but analog presentations may be better for certain artistic effects. For movies, take your pick.