Light-on-dark Color Scheme

A light-on-dark color scheme is a color scheme that uses light-colored text on a dark background and is often discussed in terms of computer user interface design.

Originally, computer user interface images were formed on CRTs. The phosphor was normally a very dark color, and lit up brightly when the electron beam hit it. The human eye adjusts to make this appear to be green or amber on black, depending on phosphors applied on a monochrome screen. RGB screens continued along a similar vein, using all the beams set to "on" to form white.

With the advent of teletext, research was done into which primary and secondary light colors and combinations worked best for this new medium. From a palette of black, red, green, yellow, blue, magenta, cyan and white, it turned out that cyan or yellow on black was typically found to be optimal.

The opposite color scheme, dark-on-light color scheme, was originally introduced in WYSIWYG word processors, to simulate ink on paper.

There seems to be a dispute among vision and perception researchers about whether it is actually easier or healthier to read text on dark or light background; there is a similar dispute between users, when using each other's computer terminals.