VGA

In short: “Video Graphics Array” — an old, purely analogue display connector, largely replaced by digital standards like HDMI and DisplayPort.

In more detail: Since VGA transmits in analogue form, a modern, digitally-working device first has to convert the signal for output — which can cause slight quality loss. VGA is still occasionally found today on older projectors, industrial equipment or office computers.

In Depth

Analogue signal transmission

VGA (introduced by IBM in 1987) transmits the video signal as continuous analogue voltage values for red, green and blue — unlike digital standards like HDMI or DisplayPort, which send the image as discrete, losslessly transmitted digital values. The characteristic 15-pin D-sub connector (often coloured blue) with its two mounting screws provided a firm, vibration-resistant fit — practical for continuous operation, but impractical for quickly replugging.

Why analogue leads to quality loss

Since modern screens work entirely digitally internally (every pixel has an exact digital brightness/colour value), a monitor connected via VGA first has to convert the incoming analogue signal back into digital values (analogue-to-digital conversion, ADC). This conversion process is error-prone: electrical noise on the cable, slight deviations in the exact timing between the graphics card and monitor (pixel clock), and the cable length itself can lead to visible blur, a slight “ghosting” effect, or colour deviations — effects that, in principle, don’t occur with purely digital transmission, since either exactly the right bit arrives, or a clearly recognisable transmission error occurs.

Missing extra features

Another technical difference: VGA transmits only video signals, no audio and no additional data — unlike HDMI, which bundles video, audio and control signals (e.g. CEC for automatically turning connected devices on/off via remote control) over a single cable. Copy-protection mechanisms like HDCP, which are required for protected video content (e.g. streaming services) with digital standards, also don’t exist for VGA — one reason some modern devices no longer support VGA outputs for certain content at all.

Resolution limits and successors

VGA was originally designed for comparatively low resolutions (the base resolution it’s named after was 640×480 pixels) and was later informally extended to considerably higher resolutions, though with increasing quality problems at very high values. Because of these limitations and the lower achievable refresh rate, VGA has been almost completely replaced by digital standards in recent years — today VGA is found practically only on older projectors, industrial controllers with a long product lifespan, or in conference rooms with existing hardware that hasn’t been replaced yet.

See also: HDMI, DP (DisplayPort)