Acronym for Video Graphics Array.

An IBM graphics hardware standard used in PCs for many years. It was developed as the successor to EGA and CGA and delivers resolutions up to 640x480 in 16 colours (aspect ratio 4:3) and up to 320x200 in 256 colours (aspect ratio 8:5), chosen from a palette of 262,144 shades (6 bit per RGB component).

IBM developed XGA as its successor, but other Proprietary extensions collectively referred to as SVGA dominated the market instead. Eventually the VBE standard emerged to alleviate the need for applications to support each SVGA chip separately.

the VGA implementations that were used were a programmers dream. They allowed programmers to mix 320x200x256 and 640x480 modes to generate "ModeX" (which refered to unchained 320x200 mode allowing programmers up to about 400x256ish by 256 colours), or other even more obscure modes (eg, ModeQ which was 256x256x256, a personal favourite of mine).

None of these modes was technically supported by the hardware specs, but most machines allowed you to use them.