History ColourCodedForYourConvenience / RealLife

*** On the other hand, in some places, the colors have successfully replaced the names in common speech (though some set-in-their-ways older riders might not have adjusted). For instance, Chicagoan who calls the [[UsefulNotes/ChicagoL Brown Line]] the "Ravenswood Route" is definitely an old-timer.[[note]]If they call it the "Ravenswood Branch" they might be an old-timer or they might be a CTA employee or railfan, since the trackage from Belmont to Kimball is still called that. However, that’s a technical term relating to the fixed infrastructure; everyone except oldheads calls the service—the trains and their schedule—the Brown Line.[[/note]]

** Blue = 20 Euro, $5 Canadian, $10 Australian, $10 New Zealand, $20 Mexican pesos, $500 Mexican pesos (new; to avoid confusion with the 20 pesos bill, this one is longer and made of paper), ₽50 Russian, 5 Soviet/Imperial rubles; Brazil has dark blue for $100 and a lighter one for $2, $20 Hong Kong

** Green = 100 Euro, 5 Pounds, $20 Canadian, $100 Australian, $20 New Zealand, ₽1000 Russian (though significantly bluish), 3 and 50 Soviet/Imperial rubles; Brazil used it for $1 before it was put out of circulation, $200 Mexican pesos, $50 Hong Kong (and also old $10 before it was mostly switched out for purple bills made of plastic)

* Once upon a time, some cities and states in the United States, including the District of Columbia, rather than the black-and-white signs normally associated with the US Highway System (not to be confused with the Interstate System), used various colors on their signs with the goal to assist driver navigation, although the reasons for the colors varied from locale to locale: sometimes they indicated a particular route, sometimes they indicated the direction the route was going, and occasionally they seemed to be more or less alternates to the black-and-white signs. (Some states, such as Arizona, used colors on their state route signs as well.) Although most states only used colored signs for a handful of years in the 1950s and 1960s, the Florida Department of Transportation developed a system it used for decades. Each route was designated with a certain color, and while colors were reused (US 41 and US 98 did receive unique colors; orange and black respectively), no two routes sharing a color intersected anywhere in the state.[[note]] There was one exception, when the green US 192 was later extended to meet also green US 27.[[/note]] The color signs were eventually discontinued when the MUTCD[[note]]Manual on Uniform Traffic Control Devices (for Streets and Highways)[[/note]] rules changed and the FHWA[[note]]Federal Highway Administration[[/note]] forbade the use of highway funds to replace non-standard signs, although [=FDoT=] elected to produce the signs at its own expense for a few years afterward, with the final color sign posted in 1996. Images and more information available [[https://www.usends.com/colors.html here]].

* Before HDMI cable, a [[https://en.wikipedia.org/wiki/RCA_connector color-coded RCA plugs]] were commonly used to carry audio and video signals. The exact number and colors of cables tended to vary between different formats:
** Composite video: Yellow.
** Component video: Green for Y (brightness), blue for Pb (difference between blue and white), red for Pr (difference between red and white).
** Stereo audio: White for the left channel, red for the right channel.

* Before HDMI cable, a [[https://en.wikipedia.org/wiki/RCA_connector three color-coded RCA plugs]] were commonly used to carry audio and video signals. The yellow one is for producing pictures, the white is for left stereo sound, and the red is for right stereo sound.

** Flashing Red: Critical system failure or other extremely dangerous condition has occurred .

* At US self-serve gas stations, pump handles for diesel fuel are usually colored green to distinguish them from regular unleaded gasoline. This is ''very'' important, as mistakenly putting diesel in a non-diesel car will ruin your whole day. And most likely your whole car. High-ethanol gasoline, meanwhile, tends to be marked with yellow pump handles to differentiate it from standard unleaded fuel; accidentally putting this into a non-[=FlexFuel=] engine isn't immediately and irreversibly harmful, but it's definitely not something you'll want to make a habit of doing, either.

** Red: Nintendo
** Green: Microsoft/X-Box
** Blue: Sony/Playstation

** Blue = 20 Euro, $5 Canadian, $10 Australian, $10 New Zealand, $20 Mexican pesos, $500 Mexican pesos (new; to avoid confusion with the 20 pesos bill, this one is longer and made of paper), ₽50 Russian, 5 Soviet/Imperial rubles; Brazil has dark blue for $100 and a lighter one for $2
** Brown = $100 Canadian, ₽100 Russian, $50 Brazilian (though nearly orange), $500 Mexican pesos (old)
** Green = 100 Euro, 5 Pounds, $20 Canadian, $100 Australian, $20 New Zealand, ₽1000 Russian (though significantly bluish), 3 and 50 Soviet/Imperial rubles; Brazil used it for $1 before it was put out of circulation, $200 Mexican pesos

** Orange = 50 Euro, 10 Pounds, $5 New Zealand, ₽5000 Russian, $100 Mexican pesos

** Purple = 500 Euro, 20 Pounds, $10 Canadian, $50 New Zealand, ₽500 Russian, 25 Soviet/Imperial rubles, $5 Brazilian, $1000 Mexican pesos
** Red = 10 Euro, $50 Canadian, $20 Australian, $100 New Zealand, 10 Soviet/Imperial rubles

* Fruits change colour depending on how ripe they are. This is thought to be why humans evolved colour vision in the first place. Additionally, Women are less prone to colorblindness than men, and some women are able to see more shades of red than men are. They believe this is a holdover from the old caveman days when women were the gatherers and had to differentiate between "safe to eat" red berries and "highly poisonous" red berries.

** War Plan Red: War with the British Empire – ridiculous as it sounds now, it was considered an unlikely but real possibility due to the UK's alliance with Japan, potential conflicts over the Empire's Caribbean holdings, lingering bad feelings over unpaid debts from the Great War, and the last whisperings of [[SpaceFillingEmpire a desire to unify "English-speaking North America"]] that had existed since 1775. This plan was probably also influenced by Admiral William Benson, Chief of Naval Operations from 1915 to 1919, who strongly disliked the English. The largest components of the Empire got their own shades: Britain itself was "Red" (this included Newfoundland, which at the time was separate from Canada), Canada was "Crimson", [[UsefulNotes/TheRaj India "Ruby"]], Australia "Scarlet", New Zealand "Garnet", and [[TheLastOfTheseIsNotLikeTheOthers Ireland "Emerald"]]. The bulk of this plan outlined a multi-front invasion and occupation of Canada while the US Navy blocked the Royal Navy from entering the Western Atlantic.

* This is quite common for any metropolitan mass transit system that's extensive enough to have multiple lines. In older systems where the lines originally had names, it's a bit of a tossup whether people use the colors to refer to the lines: for instance, in [[UsefulNotes/PhiladelphiaSubways Philadelphia]], while the two main mass-transit routes are consistently colored (the Broad Street Subway is always colored orange, the Market-Frankford Elevated is always blue), even extending to the colors of the signage and the colors of the seats in the cars, Philadelphians almost invariably call them the "Subway" (or the "Sub") and the "El" rather than the Orange Line and Blue Line.[[note]]In 2021, SEPTA announced plans to use a letters-and-numbers naming scheme somewhat similar to the NYC Subway; this is still in the planning phases, though. Also, this reflects usage in English; interestingly, Spanish-speakers in Philadelphia (a sizeable community) tend to use the colors--e.g. the "El" in Spanish is usually "la Línea Azul".[[/note]] Similarly, no Londoner would dream of calling any of the [[UsefulNotes/TheLondonUnderground Tube]] lines by their colours, even though they have been coloured consistently on Tube maps since the 1930s (save for lines added since then, of course).[[note]]It would be entirely possible to use a colour-based nomenclature for the Tube. Going alphabetically: Bakerloo=Brown Line, Central=Red Line, Circle=Yellow Line, District=Green Line, Hammersmith & City=Pink Line, Jubilee=Grey Line, Metropolitan=Magenta or Purple Line, Northern=Black Line, Picadilly=Blue Line, Victoria=Aqua or Azure Line, Waterloo & City = Turquoise Line. However, nobody wants to do it this way, so it isn't.[[/note]] On the other hand, in some places, the colors have successfully replaced the names in common speech; a Chicagoan who calls the [[UsefulNotes/ChicagoL Brown Line]] the "Ravenswood Route" is definitely an old-timer.[[note]]If they call it the "Ravenswood Branch" they might be an old-timer or they might be a CTA employee or railfan, since the trackage from Belmont to Kimball is still called that. However, that’s a technical term relating to the fixed infrastructure; everyone except oldheads calls the service—the trains and their schedule—the Brown Line.[[/note]] Finally, in some newer systems, the lines never had another name to begin with; the colors ''are'' the names. (The UsefulNotes/WashingtonMetro is a prime example, as it was built from scratch in the 1970s.)

* This is quite common for any metropolitan mass transit system that's extensive enough to have multiple lines. In older systems where the lines originally had names, it's a bit of a tossup whether people use the colors to refer to the lines: for instance, in [[UsefulNotes/PhiladelphiaSubways Philadelphia]], while the two main mass-transit routes are consistently colored (the Broad Street Subway is always colored orange, the Market-Frankford Elevated is always blue), even extending to the colors of the signage and the colors of the seats in the cars, Philadelphians almost invariably call them the "Subway" (or the "Sub") and the "El" rather than the Orange Line and Blue Line. Similarly, no Londoner would dream of calling any of the [[UsefulNotes/TheLondonUnderground Tube]] lines by their colours, even though they have been coloured consistently on Tube maps since the 1930s (save for lines added since then, of course).[[note]]It would be entirely possible to use a colour-based nomenclature for the Tube. Going alphabetically: Bakerloo=Brown Line, Central=Red Line, Circle=Yellow Line, District=Green Line, Hammersmith & City=Pink Line, Jubilee=Grey Line, Metropolitan=Magenta or Purple Line, Northern=Black Line, Picadilly=Blue Line, Victoria=Aqua or Azure Line, Waterloo & City = Turquoise Line. However, nobody wants to do it this way, so it isn't.[[/note]] On the other hand, in some places, the colors have successfully replaced the names in common speech; a Chicagoan who calls the [[UsefulNotes/ChicagoL Brown Line]] the "Ravenswood Route" is definitely an old-timer.[[note]]If they call it the "Ravenswood Branch" they might be an old-timer or they might be a CTA employee or railfan, since the trackage from Belmont to Kimball is still called that. However, that’s a technical term relating to the fixed infrastructure; everyone except oldheads calls the service—the trains and their schedule—the Brown Line.[[/note]] Finally, in some newer systems, the lines never had another name to begin with; the colors ''are'' the names. (The UsefulNotes/WashingtonMetro is a prime example, as it was built from scratch in the 1970s.)

** Purple = Grape

** '''Brown''': After World War One, Brown became the color of Nazism. Nazis party officials and most of its organisations (except the [=SS=] and some of youth organisations) wore brown uniforms - the first ones had been surplus army shirts intended for use on the Turkish fronts (note that the regular German and Austrian army uniforms in the war had been in different shades of grey). The Nazi party central office in Munich was known as the Brown House.

* UsefulNotes/RussiansWithRustingRockets takes it to the extreme with colour-coded undershirts. No, seriously. It started back in XVIII century when sailors traditionally wore striped undershirts (telnyashkas) and so did the naval infantry. Their stripes were either deep-blue or black. Everybody knows that sailors are badass and marines are even more badass, so when, after UsefulNotes/WorldWarII, airborne corps were created, they received light-blue-striped telnyashkas. The first commander of airborne corps, Vasiliy Margelov, was a former marine, you see. Then, around 90's, the idea got around that you cannot be badass if you don't have telnyashka, so various forces started to introduce their own colour schemes.

** Blue: Not approved by the Church, but sometimes worn anyway by priests during Advent (as a way of distinguishing it from Lent as above). In some countries.[[note]]Spain and the Philippines being chief among them.[[/note]] it has been approved as a vestment color for feasts of the Virgin Mary (as blue is the color of the Virgin Mary)

* Scotch tape, while known for just their "sticky but not too sticky" tape, they have multiple types of tape, all in similarly sized dispensers, but with different colors in their plaid patterns to distinguish them.

** Red: the color of blood, passion, and revolution, Red is usually associated with populist, radical, and occasionally violent, political movements. Nowadays most commonly associated with Marxism and Organized Labour, but in the past a wide range of radical political movements claimed Red as their color (most famously the Red Shirts of Garibaldi's volunteer army).
** White: color of purity and peace. Nowadays mostly associated with Pacifism.

** Black: Politically, the color Black has a long association with anonymity, lawlessness, and "non-personhood." Where colors or patterns of colors would signify personal identity and political allegiance, solid black, as the absence of color, meant the absence of allegiance. As far back as the Middle Ages, "black knights" carried no family crest or color on their shields, symbolizing their independence (or simply concealing their identities). Beginning in the 19th Century Black was adopted by Anarchist groups: the color of no country or government. More radical Anarchists groups often also use Black in conjunction with Red.

** Brown: After World War One, Brown became the color of Nazism. Nazis party officials and most of its organisations (except the [=SS=] and some of youth organisations) wore brown uniforms - the first ones had been surplus army shirts intended for use on the Turkish fronts (note that the regular German and Austrian army uniforms in the war had been in different shades of grey). The Nazi party central office in Munich was known as the Brown House.

** Green: color associated with nature, Green is the color of most Environmentalist movements.

** Gold: the "color of money," associated with Free Market Capitalism, and sometimes, by extension, Libertarianism.
** Purple: In modern European politics, Purple is usually associated with coalition governments, being a combination of Red (radical left) and Blue (traditional conservative).

** Pink: associated with LGBT and Women's Health movements.

* Everyone knows what traffic lights mean - red means stop, green means go, yellow means prepare to stop here as the light will soon be red. However, in many places, at least across the US, a fourth light is used - white. This indicates ''vehicle exemption'' - that an approaching vehicle cannot stop at this intersection and must be allowed to proceed regardless of whether its lane has a green light. Typically, this is for law enforcement or emergency services, but can also apply to trains that have to use tracks that happen to run through an intersection.

** The modern [[UsefulNotes/NotTheWehrmacht German Army]] (''Heer'') and Air Force (''Luftwaffe'') continue the tradition, though with some changes in colour:

* At US self-serve gas stations, pump handles for diesel fuel are usually colored green to distinguish them from regular unleaded gasoline. This is ''very'' important, as mistakenly putting diesel in a non-diesel car will ruin your whole day. And most likely your whole car.

* This is quite common for any metropolitan mass transit system that's extensive enough to have multiple lines. In older systems where the lines originally had names, it's a bit of a tossup whether people use the colors to refer to the lines: for instance, in [[UsefulNotes/PhiladelphiaSubways Philadelphia]], while the two main mass-transit routes are consistently colored (the Broad Street Subway is always colored orange, the Market-Frankford Elevated is always blue), even extending to the colors of the signage and the colors of the seats in the cars, Philadelphians almost invariably call them the "Subway" (or the "Sub") and the "El" rather than the Orange Line and Blue Line. Similarly, no Londoner would dream of calling any of the [[UsefulNotes/TheLondonUnderground Tube]] lines by their colours, even though they have been coloured consistently on Tube maps since the 1930s.[[note]]It would be entirely possible: Bakerloo=Brown Line, Central=Red Line, Circle=Yellow Line, District=Green Line, Hammersmith & City=Pink Line, Jubilee=Grey Line, Metropolitan=Magenta or Purple Line, Northern=Black Line, Picadilly=Blue Line, Victoria=Aqua or Azure Line, Waterloo & City = Turquoise Line. Nobody wants to do it this way so it isn't.[[/note]] On the other hand, in some places, the colors have successfully replaced the names in common speech; a Chicagoan who calls the [[UsefulNotes/ChicagoL Brown Line]] the "Ravenswood Route" is definitely an old-timer.[[note]]If they call it the "Ravenswood Branch" they might be an old-timer or they might be a CTA employee or railfan, since the trackage from Belmont to Kimball is still called that. However, that’s a technical term relating to the fixed infrastructure; everyone except oldheads calls the service—the trains and their schedule—the Brown Line.[[/note]] Finally, in some newer systems, the lines never had another name to begin with; the colors ''are'' the names. (The UsefulNotes/WashingtonMetro is a prime example, as it was built from scratch in the 1970s.)

* This is quite common for any metropolitan mass transit system that's extensive enough to have multiple lines. In older systems where the lines originally had names, it's a bit of a tossup whether people use the colors to refer to the lines: for instance, in [[UsefulNotes/PhiladelphiaSubways Philadelphia]], while the two main mass-transit routes are consistently colored (the Broad Street Subway is always colored orange, the Market-Frankford Elevated is always blue), even extending to the colors of the signage and the colors of the seats in the cars, Philadelphians almost invariably call them the "Subway" (or the "Sub") and the "El" rather than the Orange Line and Blue Line. On the other hand, in some places, the colors have successfully replaced the names in common speech; a Chicagoan who calls the [[UsefulNotes/ChicagoL Brown Line]] the "Ravenswood Route" is definitely an old-timer.[[note]]If they call it the "Ravenswood Branch" they might be an old-timer or they might be a CTA employee or railfan, since the trackage from Belmont to Kimball is still called that. However, that’s a technical term relating to the fixed infrastructure; everyone except oldheads calls the service—the trains and their schedule—the Brown Line.[[/note]] Finally, in some newer systems, the lines never had another name to begin with; the colors ''are'' the names. (The UsefulNotes/WashingtonMetro is a prime example, as it was built from scratch in the 1970s.)

* Before HDMI cable, [[https://en.wikipedia.org/wiki/RCA_connector a three RCA plugs]] were commonly used to carry audio and video signals. The yellow one is for producing pictures, the white is for left stereo sound, and the red is for right stereo sound.

* Before HDMI cable, [[https://en.wikipedia.org/wiki/RCA_connector the three RCA plugs]] were commonly used to carry audio and video signals. The yellow one is for producing pictures, the white is for left stereo sound, and the red is for right stereo sound.