Technically speaking, white is a color, but it is also the combination of all the colors of the visible light spectrum. It is sometimes described as an achromatic color, like black.

As a misnomer, however, white is the color of things that reflect light of all parts of the visible spectrum equally and are not dull (see grey).

The shade has the highest possible brightness of 100%, and has no hue. The impression of white light can be created by mixing, via a process called additive mixing, appropriate intensities of the primary color spectrum: red, green and blue, but the illumination provided by this technique has significant differences from that produced by incandescence.

In nature, the color white results when transparent fibers, particles, or droplets are in a transparent matrix of a substantially different refractive index. Examples include classic "white" substances such as sugar, foam, pure sand or snow, cotton, clouds, milk, etc. Crystal boundaries and imperfections can also make otherwise transparent materials white, as in the case of milky quartz or the microcrystalline structure of a seashell. This is also true for artificial paints and pigments, where the color white results when finely divided transparent material of a high refractive index is suspended in a contrasting binder. Typically paints contain calcium carbonate and/or synthetic rutile with no other pigments if a white color is desired.

Shade

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Paint
In painting, white can be crafted by reflecting ambient light from a white pigment, although the ambient light must be white light, or else the white pigment will appear the color of the light. White when mixed with black produces gray. To art students, the use of white can present particular problems, and there is at least one training course specializing in the use of white in art. There are also speculations about the use of white and other colors.

White light
Until Newton's work became accepted, most scientists believed that white was the fundamental color of light; and that other colors were formed only by adding something to light. Newton demonstrated this was not true by passing white light through a prism, then through another prism. If the colors were added by the prism, the second prism should have added further colors to the single-colored beam. Since the single-colored beam remained a single color, Newton concluded that the prism merely separated the colors already present in the light. White light is the effect of combining the visible colors of light in equal proportions.

In the science of lighting, there is a continuum of colors of light that can be called "white". One set of colors that deserves this description is the color emitted via the process called incandescence, by a black body at various relatively-high temperatures. For example, the color of a black body at a temperature of 2848 kelvins matches that produced by domestic incandescent light bulbs. It is said that "the color temperature of such a light bulb is 2848 K". The white light used in theatre illumination has a color temperature of...