In antiquity and the Middle Ages, grey was the color of undyed wool, and thus was the color most commonly worn by peasants and the poor. It was also the color worn by Cistercian monks and friars of the Franciscan and Capuchin orders as a symbol of their vows of humility and poverty. Franciscan friars in England and Scotland were commonly known as the grey friars, and that name is now attached to many places in Great Britain.
During the Renaissance and the Baroque, grey began to play an important role in fashion and art. Black became the most popular color of the nobility, particularly in Italy, France, and Spain, and grey and white were harmonious with it.

Grey was also frequently used for the drawing of oil paintings, a technique called grisaille. The painting would first be composed in grey and white, and then the colors, made with thin transparent glazes, would be added on top. The grisaille beneath would provide the shading, visible through the layers of color. Sometimes, the grisaille was simply left uncovered, giving the appearance of carved stone.

Grey was a particularly good background color for gold and for skin tones. It became the most common background for the portraits of Rembrandt van Rijn and for many of the paintings of El Greco, who used it to highlight the faces and costumes of the central figures. The palette of Rembrandt was composed almost entirely of somber colors. He composed his warm greys out of black pigments made from charcoal or burnt animal bones, mixed with lead white or a white made of lime, which he warmed with a little red lake color from cochineal or madder. In one painting, the portrait of Margaretha de Geer (1661), one part of a grey wall in the background is painted with a layer of dark brown over a layer of orange, red, and yellow earths, mixed with ivory black and some lead white. Over this he put an additional layer of glaze made of mixture of blue smalt, red ochre, and yellow lake. Using these ingredients and many others, he made greys which had, according to art historian Philip Ball, "an incredible subtlety of pigmentation". The warm, dark and rich greys and browns served to emphasize the golden light on the faces in the paintings.
Grey became a highly fashionable color in the 18th century, both for women's dresses and for men's waistcoats and coats. It looked particularly luminous coloring the silk and satin fabrics worn by the nobility and wealthy.

Women's fashion in the 19th century was dominated by Paris, while men's fashion was set by London. The grey business suit appeared in the mid-19th century in London; light grey in summer, dark grey in winter; replacing the more colorful palette of men's clothing early in the century.

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The whiteness or darkness of clouds is a function of their depth. Small, fluffy white clouds in summer look white because the sunlight is being scattered by the tiny water droplets they contain, and that white light comes to the viewer's eye. However, as clouds become larger and thicker, the white light cannot penetrate through the cloud, and is reflected off the top. Clouds look darkest grey during thunderstorms, when they can be as much as 20,000 to 30,000 feet high.

Stratiform clouds are a layer of clouds that covers the entire sky, and which have a depth of between a few hundred to a few thousand feet thick. The thicker the clouds, the darker they appear from below, because little of the sunlight is able to pass through. From above, in an airplane, the same clouds look perfectly white, but from the ground the sky looks gloomy and grey.
The color of a person's hair is created by the pigment melanin, found in the core of each hair. Melanin is also responsible for the color of the skin and of the eyes. There are only two types of pigment: dark (eumelanin) or light (phaeomelanin). Combined in various combinations, these pigments create all natural hair colors.

Melanin itself is the product of a specialized cell, the melanocyte, which is found in each hair follicle, from which the hair grows. As hair grows, the melanocyte injects melanin into the hair cells, which contain the protein keratin and which makes up our hair, skin, and nails. As long as the melanocytes continue injecting melanin into the hair cells, the hair retains its original color. At a certain age, however, which varies from person to person, the amount of melanin injected is reduced and eventually stops. The hair, without pigment, turns grey and eventually white. The reason for this decline of production of melanocytes is uncertain. In the February 2005 issue of Science, a team of Harvard scientists suggested that the cause was the failure of the melanocyte stem cells to maintain the production of the essential pigments, due to age or genetic factors, after a certain period of time. For some people, the breakdown comes in their twenties; for others, many years later. According to the site of the magazine Scientific American, "Generally speaking, among Caucasians 50 percent are 50 percent grey by age 50." Adult male gorillas also develop silver hair, but only on their backs – see Physical characteristics of gorillas.
Over the centuries, artists have traditionally created grey by mixing black and white in various proportions. They added a little red to make a warmer grey, or a little blue for a cooler grey. Artists could also make a grey by mixing two complementary colors, such as orange and blue.

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In the Christian religion, grey is the color of ashes, and so a biblical symbol of mourning and repentance, described as sackcloth and ashes. It can be used during Lent or on special days of fasting and prayer. As the color of humility and modesty, grey is worn by friars of the Order of Friars Minor Capuchin and Franciscan order as well as monks of the Cistercian order. Grey cassocks are worn by clergy of the Brazilian Catholic Apostolic Church.

Buddhist monks and priests in Japan and Korea will often wear a sleeved grey, brown, or black outer robe.

Taoist priests in China also often wear grey.
Grey is rarely used as a color by political parties, largely because of its common association with conformity, boredom and indecision. An example of a political party using grey as a color are the German Grey Panthers.

The term "grey power" or "the grey vote" is sometimes used to describe the influence of older voters as a voting bloc. In the United States, older people are more likely to vote, and usually vote to protect certain social benefits, such as Social Security.

Greys is a term sometimes used pejoratively by environmentalists in the green movement to describe those who oppose environmental measures and supposedly prefer the grey of concrete and cement.
During the American Civil War, the soldiers of the Confederate Army wore grey uniforms. At the beginning of the war, the armies of the North and of the South had very similar uniforms; some Confederate units wore blue, and some Union units wore grey. There naturally was confusion, and sometimes soldiers fired by mistake at soldiers of their own army. On June 6, 1861, the Confederate government issued regulations standardizing the army uniform and establishing cadet grey as the uniform color. This was (and still is) the color of the uniform of cadets at the United States Military Academy at West Point, and cadets at the Virginia Military Institute, which produced many officers for the Confederacy.

The new uniforms were designed by Nicola Marschall, a German-American artist, who also designed the original Confederate flag. He closely followed the design of contemporary French and Austrian military uniforms. Grey was not chosen for its camouflage value; this benefit was not appreciated for several more decades. The South lacked a major dye industry, though, and grey dyes were inexpensive and easy to manufacture. While some units had uniforms colored with good-quality dyes, which were a solid bluish-grey, others had uniforms colored with vegetable dyes made from sumac or logwood, which quickly faded in sunshine to the yellowish color of butternut squash.

The German Army wore grey uniforms from 1907 until 1945, during both the First World War and Second World War. The color chosen was a grey-green called field grey (German: feldgrau). It was chosen because it was less visible at a distance than the previous German uniforms, which were Prussian blue. It was one of the first uniform colors to be chosen for its camouflage value, important in the new age of smokeless powder and more accurate rifles and machine guns. It gave the Germans a distinct advantage at the beginning of the First World …

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