Darkness (also called lightlessness) is the absence of light. Scientifically it is only possible to have a reduced amount of light. The emotional response to an absence of light has inspired metaphor in literature, symbolism in art, and emphasis.
A dark object reflects fewer visible photons than other objects, and therefore appears dim in comparison. For example, matte black paint does not reflect visible light and appears dark, but white paint reflects all visible light and appears bright. For more information see color.
However; light cannot simply be absorbed without limit. Energy, like visible light, cannot be created or destroyed. It can only be converted from one type of energy to another. Most objects that absorb visible light reemit it as infrared light. So, although an object may appear dark, it is likely bright at a frequency that a human being cannot see. For more information see thermodynamics.
A dark area has few, if any, light sources present, making everything hard to see, like at night. Exposure to alternating light and darkness (night and day) has caused several evolutionary adaptations to darkness. When a vertebrate, like a human, is placed in a dark area, its iris dilates, allowing more light to enter the eye and improving night vision.
The scientific definition of light includes the entire electromagnetic spectrum, not just visible light, so it is scientifically impossible to create perfect darkness. For example, all objects radiate heat in the form of infrared light and gamma rays, extremely high frequency light, can penetrate even dense materials.
As a poetic term, darkness can also mean the presence of shadows, evil, or depression.
Darkness can have a strong psychological impact. It can cause depression in people with seasonal affective disorder, fear in nyctophobics, comfort in lygophilics, or attraction as in gothic fashion. These emotions are used to add power to literary imagery.
Religious texts often use darkness to make a visual point. In the Bible, darkness was the second to last plague (Exodus 10:21) and the location of “weeping and gnashing of teeth.” (Matthew 8:12) The Qur’an has been interpreted to say that those who transgress the bounds of what is right are doomed to “burning despair and ice-cold darkness.” (Nab 78.25) In Greek Mythology, three layers of night surround Tartarus, a place for the worst sinners as far beneath Hades as heaven is high above earth.
The use of darkness as a rhetorical device has a long standing tradition. Shakespeare, working in the 16th and 17th centuries, made a character call Satan the “prince of darkness” (King Lear: III, iv) and gave darkness jaws with which to devour love. (A Midsummer Night’s Dream: I, i) Chaucer, a 14th century Middle English writer, wrote that knights must cast away the “workes of darkness.” Dante described hell as “solid darkness stain’d.”
Even in Old English there were three words that could mean darkness; heolstor, genip, and sceadu. Heolstor also meant “hiding-place” and became holster, genip meant “mist” and fell out of use like many strong verbs, it is however still used in the Dutch saying "in het geniep" which means secretly, sceadu meant “shadow” and remained in use. The word darkness eventually evolved from the word deorc, which meant “dark”.
Artistically, darkness can also be used to emphasize or contrast with light. See chiaroscuro for a discussion of the uses of such contrasts in visual media.
Color paints are mixed together to create darkness, because each color absorbs certain frequencies of light. Theoretically, mixing together the three primary colors, or the three secondary colors, will absorb all visible light and create black. In practice it is difficult to prevent the mixture from taking on a brown tint.
The color of a point, on a standard 24-bit computer display, is defined by three numbers between 0 and 255, one each for red, green, and blue. Because the absence of light creates darkness, darker colors are closer to (0,0,0).
Pens use darkness, commonly in the form of blue or black ink, to make clear markings on bright paper, commonly white or yellow. Letters displayed on a computer display are also usually created dark, often in the same blue and black colors, on a light background. This difference in brightness levels is called contrast and makes smaller letters readable.