Grey (International and some parts of the U.S.) or gray (Some U.S. only – see spelling differences) describes the tints and shades ranging from black to white. These, including white and black, are known as achromatic colors or neutral colors. In recent years, "neutral colors" had been reclassified. These "new" neutrals have low colorfulness and/or chroma on the color wheel.

Greys are seen commonly in nature and fashion. Grey paints can be created by mixing complementary colors (that is colors directly opposite on the color wheel, e.g. yellow and violet). In the RGB color model used by computer displays, it is created by mixing equal amounts of red, green, and blue light. 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 English was in 700.

In color theory

Most grey pigments have a cool or warm cast to them, as the human eye can detect even a minute amount of saturation.Fact: date=September 2007

Two colors are called complementary colors if grey is produced when they are combined. 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.Fact: date=August 2007

Web colors

There are several shades 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 greyscale, but are slightly saturated towards cyan (green + blue). Note that since there are an even (256, including black and white) number of unsaturated shades 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 coordinates

RGB

Grey values result when r = g = b, for the color (r, g, b)

Grey values are produced by c = m = y = 0, for the color (c, m, y, k). Lightness is adjusted by varying k. In theory, any mixture where c = m = y is neutral, but in practice such mixtures are often a muddy brown (see CMYK#Why black ink is used).