Complementary colors are defined to mix to grey, either additively or subtractively, and many color models place complements opposite each-other in a color wheel. To produce grey in RGB displays, the R, G, and B primary light sources are combined in proportions equal to that of the white point. In four-color printing, greys are produced either by the black channel, or by an approximately equal combination of CMY primaries. Images which consist wholly of neutral colors are called monochrome, black-and-white or greyscale.

The first recorded use of grey as a color name in the English language was in AD 700.

Most grey pigments have a cool or warm cast to them, as the human eye can detect even a minute amount of saturation.[citation needed] Yellow, orange, and red create a "warm grey". Green, blue, and violet create a "cool grey". When there is no cast at all, it is referred to as "neutral grey", "achromatic grey" or simply "grey".

Two colors are called complementary colors if grey is produced when they are combined(in the light spectrum, but as in art it produces brown with paints usually). Grey is its own complement. Consequently, grey remains grey when its color spectrum is inverted, and so has no opposite, or alternately is its own opposite.

Artists sometimes use the two different spellings to distinguish between strict combinations of black and white versus combinations that have elements of hue.[citation needed]

There are several tones of grey available for use with HTML and CSS in word form, while there are 254 true greys available through Hex triplet. All are spelled with an a: using the e spelling can cause unexpected errors (this spelling was inherited from the X11 color list), and to this day, Internet Explorer's Trident browser engine does not recognize "grey" and will render it as green. Another anomaly is that "gray" is in fact much darker than the X11 color marked "darkgray"; this is because of a conflict with the original HTML gray and the X11's "gray", which is closer to HTML's "silver". The three "slategray" colors are not themselves on the grey scale, but are slightly saturated towards cyan (green + blue). Note that since there are an even (256, including black and white) number of unsaturated tones of grey, there are actually two grey tones straddling the midpoint in the 8-bit greyscale. The color name "gray" has been assigned the lighter of the two shades (128 also known as #808080), due to rounding up. In browsers that support it, "grey" has the same color as "gray".

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Color vision · Color blindness · Visible spectrum · Color constancy · Color term · Color theory · Complementary color

Hue · Lightness · Colorfulness · Additive color · Subtractive color · Primary color · Secondary color