Vision is the one sense we rely on the most. We usually identify things by sight rather than sound or smell. It is for this reason that creators of visual media will make sure that things look different enough for the audience to easily recognize and tell apart. It can also be a form of visual shorthand for characterization, so that the audience can tell certain things about a character or setting without having to be told.
In addition, to the audience, this trope may be used in-Universe so that the characters can easily tell the difference between groups or things.
One way to do this is to use color as an indicator that two things are different (when using different colors) or two things belong to the same category (when using the same colors). Color can indicate who is the good guy and who is the bad guy, they can indicate personality type, they can say things about gameplay elements in a video game, which organization or group the person belongs to, and so on.
Typically, in teams, or more generally among the main cast, characters may be associated with certain colors in promotional material, or have them prominently displayed on their outfit or uniform. If this is the case, expect the primary colors Red/Blue/Green/Yellow to show up somewhere.
Compare Good and Evil for Your Convenience. ——
Revolutionary Girl Utena with the Duelists' roses. Other than Utena, who is a Rose-Haired Girl and bears a white rose, the rest below match their hair colors as well:
Utena: White/Pink
Touga: Red
Saionji: Green
Juri: Orange
Miki: Light Blue
Nanami: Yellow
Ruka: Dark Blue
Professor Nemuro and The Black Rose Duelists all have black roses
In Kuroko No Basuke, all of the Generation of Miracles have hair colors that match with the kanji in their names, except for Kuroko. They also combine this with Curtains Match the Window.
Kise, Yellow
Midorima, Green
Aomine, Blue
Murasakibara, Purple
Akashi, Red
Momoi, Pink
Comic Books
Teenage Mutant Ninja Turtles: An interesting example. While this trope has overall been played straight across the franchise, it was averted with the old comic, where not only did all of the turtles have the same skin tone, their bandannas were all red (whenever they got colored at all), making it hard to tell the four apart even when they did have their trademark weapons. The new IDW comics are continuing the tradition.
On the other side of the spectrum are the original toys, where not only did Leonardo, Donatello, Michelangelo, and Raphael all have their specifically-colored bandannas, their green skin tones were all in unique shades as well. This was duplicated in the second cartoon, making the turtles easier to differentiate from each other. See the Western Animation section below.
The rest of the installments have just opted for similar skin tones, with the bandannas and weapons being the aids to tell the guys apart.
Fan Fiction
Fiona's five personalities from Kira Is Justice each has their own color. In order of speaking order: White, Blue, Yellow, Green, and Pink.
Films
Wall Street: Money Never Sleeps. All of the characters wear suits in morally ambiguous shades of grey. The villain, Bretton James, wears a demonic red suit.
In Rebel Without a Cause, the color red is used often as a motif. For example, Judy's coat in the beginning of the movie, Jim's jacket, one of Plato's socks, etc.
Toy Story 3: Blue = safe (Andy's room; Butterfly room; conveyor belt off switch); red = unsafe ( Lotso; the incinerator); Sickly Green Glow = corrupted ( the snack machine "gambling den"; the Dumpster).
Disney's Aladdin has color motifs based on its desert setting. Blue (water) = good, red (heat) = evil, and yellow (sand) = neutral.
Played with in Reservoir Dogs: each of the robbers is given a colour-based codename (Mr. White, Mr. Orange, Mr. Pink, etc), but they all wear identical black suits, shades and have slicked-back hair precisely in order to make identification (in the context of a police lineup) more difficult.
In Logan's Run, the people who lived in the city wore clothes that matched their ages and the color of their life clocks. The sandmen, who were essentially portrayed as being evil, wore black and gray, even when they were in the gym or at home.
In The Hunt for Red October, different color lighting was used for each submarine's interior to aid the viewer in quick recognition of which submarine it was and to minimize confusion.
Heathers: All three Heathers, Veronica, and J.D. wear their own color of clothing — Chandler is red, McNamara is yellow, Duke is green, Veronica is blue and J.D. is black, though this isn't noticeable at first. Chandler's red hair bow becomes a symbol of power, as after her death, Duke claims it for herself, symbolizing her replacement of the original Heather. Veronica forcefully taking it from Duke at the end of the film shows the end of the Heathers' power.
In the 1920 silent film The Mark of Zorro, Zorro instructs his allies to ride black horses on their night's mission to rescue some unjustly-jailed prisoners. The soldiers that pursue them conveniently all have light-colored horses, making it easy for viewers to keep track of which band of riders is which.
If an animal is important and doesn't have extra features (Pegasus, Sleipnir, Cerberus), it will most often be a certain color. White is a particularly strong giveaway, as many cultures believe that white animals have magical properties.
This is addressed (or lampshaded or something) in GURPSInfinite Worlds, which lists being entirely white as one of the signs that an animal may be a parachronozoid (in-world jargon for "naturally capable of moving between worlds").
Literature
Used in Orphans of Chaos. When using her higher senses, Amelia can see the utility of nearby objects to her or someone else by how brightly they glow with a white light.
Lampshaded by Diana Wynne Jones in The Tough Guide To Fantasyland, wherein she explained that a Genre Savvy character can always identify which characters are (or will will turn out) good, evil, traitorous, possessing magical powers, or lost royal heirs upon first meeting them by the color of their hair or eyes (or combination thereof).
In Dragonriders of Pern, the dragons are visually distinguishable by gender and caste by their color. Additionally, many of the disciplines have a distinctive color that members of the guildhall wear. Miners, crafters, harpers, and healers each have a distinctive uniform color, with further variations in tone for apprentices, journeyman, and masters.
The Stainless Steel Rat's Revenge. The planet of Cliaand is completely militarized, and every person on it has a uniform with a color appropriate to their job.
In Dragonlance the Towers of Sorcery actually enforce this trope. White represents good, Black evil, and Red neutral. This is partly because the world's history has shown a need for balance between these moral axes. Extremes of corruption and piety have brought ruin to the world.
Subverted in one Dragonlance short story. A knight slays what he thinks is a white dragon, which are Always Chaotic Evil. It turns out, however, that the dragon in question was an albino silver dragon (silver dragons are Always Lawful Good).
There was a series by Garth Nix called The Seventh Tower featuring an entire caste system based on the rainbow; the more powerful a particular color in the society's magic system, the higher the rank of the corresponding caste. Everyone owned a crystal with which they could perform light-based magic; any individual could use colors and visit floors of the complex (in which the entire society lived) equal to or lesser than their own rank, but needed special dispensation to go higher in the pecking order without actually going to the trouble of earning an increase in social station. In the lowest floors was a caste of servants who weren't given a color at all, who were regarded as being not wholly dissimilar to lepers.
Live Action TV
On Scrubs, the medical doctors wear blue scrubs, and the surgeons wear green. Nurses most often wear pink or purple, and orderlies are in maroon.
Naturally, the members of numerous Super Sentai/Power Rangers teams in each season are distinguished by the colors of their outfits. The most common color combination consists of red (usually the leader), green, blue, yellow, and pink. Some seasons will have black or white ranger in lieu of one of the above colors. In a manner similar to the GI Joe laser situation, some colorcoded aspects will change when a Ranger acquires a different shiny suit.
Power Rangers took it Up to Eleven in their first few seasons. Not only did they always wear their designated ranger colors unmorphed, most of their accessories (backpacks, notebooks, etc.) were also color-coded, alongside Pink Ranger Kimberly having a pink car (really a dark magenta, but that was what they were going for) and Yellow Ranger Trini drinking a banana milkshake at the juice bar (yes, out of a yellow glass.) A couple of former Rangers have mentioned hating seeing their Ranger color once they leave the show.
Lampshaded in Dino Thunder. At the end of the episode when he gains the new Black Ranger powers, Tommy comments that he doesn't know what he's going to wear since he doesn't have any black clothes in his wardrobe.
The Kamen Rider Series now becomes guilty of this trope because of merchandising. Almost every main Rider will have several modes, color-designated.
In series 5 of the revived Doctor Who, the New Paradigm Daleks are
Scientist - orange
Strategist - blue
Drone - red
Eternal - yellow
Supreme - white
Sons Of Anarchy: While it's not prominent, the gangs display their own colours. Samcro wears a lot of blue, Mayans have green and the One-Niners purple.
Degrassi Community School introduces uniforms in Season 10 of the eponymous show, color-coded by year (Seniors-blue, juniors-red, sophomores-purple, freshmen-yellow). This holds in subsequent years, apparently literally for the viewers' convenience, where in a real school it would make more sense for the rising students to keep their present colors with blue rotated to the incoming freshmen.
The Fresh Beat Band: Shout wears orange, Kiki pink, Marina blue, and Twist yellow.
Uniforms in Stargate Atlantis are colour coded in a similar manner to Star Trek. Sciences are in blue, medical are in yellow, command is in red, and military are in black.
In the 2005 remake we can see that at least Ochre and Blue get colour coded bikes as well.
Tabletop Games
The use of color to distinguish sides is so common that it's easier to note exceptions. For instance, in shogi, the pieces of the two sides are identical and distinguished by which way they're pointing.
For the longest time in Dungeons & Dragons, one could easily distinguish between good & evil dragons by whether or not they were metallic and shiny (good) or vividly monochromatic (evil). This was eliminated in 4th edition, though it still gives an idea of whether or not a dragon is more likely to be more "social" or more predatory.
Alpha Complex in Paranoia is colour coded for your inconvenience. It's almost certain that to get anywhere interesting, you'll have to cross an area outside your colour clearance. (Paint is strictly rationed and outside your clearance.)
In a meta example, New Horizon requires two differently colored twenty-sided dice. The rulebook labels them White and Black; you can only get criticals on the black dice.
Kessen II: Once again, Shu's officers dress in Green, but Wei and Wu switched. Wei officers in this game wear Red and Wu's army dress in Blue.
In Resonance of Fate, weapons, damage displays, and damage is displayed in either blue or red, depending on if they do Scratch or Direct Damage, respectively.
BioShock and its sequel color-code the security turrets, bots, and cameras: red ones are hostile, and green ones have been hacked to be on your side. The lights on the Big Daddies' suits' portholes are similar: yellow light means it's neutral, green means it's hypnotized, and red means it's hostile.
Donkey Kong 64 was practically built around this idea. If anything important pertained to a certain character, one simply had to look at the color to figure out to whom the task belongs. For Donkey Kong, it was yellow; there was red for Diddy, blue for Lanky, purple for Tiny, and green for Chunky.
Borderlands: Anything that can be interacted with (chests, switches, quest items) has a green light or aura. Considering Pandora is a barren wasteland, greenery really stands out.
Mario & Luigi: Bowser's Inside Story has several bosses and minigames where Mario and Luigi can each only deal with half of the threats—for instance, a scrolling shooter-style minigame where each of the things to be shot can only be shot by a specific brother. Mario and Luigi wear red and green, respectively, so whatever Mario targets is red, and whatever Luigi targets is green.
Luigi, Green, Dark-Green, or Blue - depending mostly on what colors Yoshi and Toad are
Yoshi, Green, Light-Green
Toad, Blue or White, or Red in the context of the Toad Brigade
Peach, Pink
Daisy, Orange/Yellow-Orange or Yellow
Bowser, Orange/Red-Orange or Dark Green
Wario, Purple(lighter), sometimes Yellow
Waluigi, Black, or Purple(darker)
DK, Yellow, or Brown
Rosalina, Cyan and White
The Lumas, White (Luma), Black (Polari), Purple (Lubba), Red (flying), Orange (Co-star), Yellow (launch star), Green (green star), Blue (Lumalee Lumabop), and Pink (Hungry Luma)
Koopa Troopas and Paratroopas, Green (walk in straight line for Troopas, hop aimlessly for Paratroopas), Red (walk back and forth for Troopas, fly up or down or side to side for Paratroopas), Blue (kicks shells), and Yellow (flashes)
Goombas, Brown (on dry land), Blue (in caves), and Gray (in castles)
Piranha Plants, Green (hides in pipes when Mario/Luigi is near it), and Red (comes out of pipes even when Mario/Luigi is near it, but will not come out if Mario/Luigi is on top of it)
Cheep Cheeps, Red (faster, can jump out of water) and Gray (was changed to green in All Stars, slower, always in water)
Bros., Lime (Hammer), Blue (Boomerang), Red (Fire), Green (Sledgehammer), Purple (AFHB), and Orange (Sumo)
Koopalings, Green (Bowser Jr.), Cyan (Larry), Black (Morton), Pink (Wendy), Lime (Iggy), Purple (Roy), Orange (Lemmy), and Blue (Ludwig)
Blue Moon - Wind and Water. Its continent is often struck by fierce wind and has many watery environments.
Yellow Moon - Lightning. Thunderstorms occur every day in its continent.
Silver Moon - Life and Death. Nothing notable happens in the world below, but a shrine hosting its original civilization is stationed near the moon itself.
There are also the five (later six) admirals of the Valuan Armada, with their uniforms and ships:
Red - Mountain / Fire / Gorons / Din(Power, Ganon)
Blue - Lake / Water(Ice) / Zoras / Nayru(Wisdom, Zelda)
Orange - Desert / Spirit / Gerudo
Purple - Graveyard / Shadow(Earth) / Sheika
Yellow - Hyrule / Light / Hylians
Guild Wars color codes just about everything. Professions are color coded, and skills for that profession have icons of predominantly that color, bosses of that profession have an aura of that color, and so on. PvP and the factions in Factions use the classic red vs blue setup. In some PvP maps, they even color-code the objectives to group them!
Inside the main Mass Effect series, the Paragon and Renegage moralities are associated with blue and red, respectively. It is especially shown with endings of the games of the main series, with the colour motif of the chosen morality being displayed in it.
In the Wing Commander series, Terran Confederation fighters are generally painted in bright colors, typically silvers and greens for the first two games and bright grey for the remaining (except for the Excalibur and Dragon superfighters, which have dark-colored hulls). Kilrathi fighters are generally ochres and darker colors. And Border Worlds Militia fighters are gunmetal grey.
In the Tomba! series, Items are split into 3 colors in the select item menu; Green, Blue, and Pink. Green Items are equippable weapons and clothes. Blue items are regular items such as the Buckets and lunch boxes. Pink Items are special automatic use items such as the Evil Pig Bags and the Treasure Chest Keys that can only be used by talking to the right NPC or doing something in the right location.
In World of Goo, different species of goo balls have different colour. It'll be difficult to tell them apart without this.
In Trauma Center there is a type of GUILT called Tetarti. It can come in groups of 3 with three, four or five colors. Their color is shown when they appear and then they turn gray. To kill them, you must inject each one with the serum that has the same color.
And each of the version mascots except in Black and White matches its version color. For the ones that aren't obvious by the name, Crystal is Purple/Light Blue, Diamond is Baby Blue, Pearl is Pink, Platinum is Gray Red and Gold.
Each of the characters' fur/feather/body color tends to follow them everywhere. Interesting case is Shadow whose fur is Black with Red highlights, he is usually associated with Blacks and Grays or Dark Red, but for some reason his attacks are all orange.
In the game Sonic Heroes, the twelve playable characters are divided into four teams of three members each. Each team consists of a speed character, a flying character, and a power character. Most obstacles are color-coded to tell the player which team member is intended to clear that obstacle with blue for speed, yellow for flying, and red for power. These colors are based on the fur colors of the "main" team featuring Sonic as the speed member, Tails as the flying member, and Knuckles as the power member.
Touhou games have red items for power, blue for score, green for Smart Bombs (except in 10 and 11, where bombs were tied to power, and green items increased the value of blue items), and purple for extra lives.
The characters in Team Fortress 2 work for two companies called RED and BLU [sic]. It's no coincidence that the Administrator and her assistant both wear purple. Even with all the unlockable weapons and modifiable accessories, the game has never allowed you to wear the colors of the opposite team (not counting disguised Spies, of course).
Advance Wars gives us Orange Star, Blue Moon, Yellow Comet and Green Earth.
Interestingly Orange Star's color is actually Red. It's name was changed from Red Star in western releases due to Unfortunate Implications.
Dwarf Fortress features dwarves that are different colors depending on their jobs, result in your main meeting room being a mess of brown, white, grey, blue, etc. smiley faces.
Golden Sun Dark Dawn does this with the protagonists' hair colours and elemental powers. The Fire adept is a redhead, the Water adept has blue hair, the Earth adept has brown hair and the hair of the Wind adept is... green. Okay, the last one isn't too obvious, but there you are.
Gears of War tends to give the CO Gs blue lights on their armor, and the Locusts have red.
Despite a fifteen year history, Resident Evil continues to clothe five out of six major characters in the same colors through every appearance. Chris is a hunter green, Jill is usually powder blue but sometimes edges towards indigo, Claire is maroon, Ada is crimson, and Wesker is black with occasional edging into dark navy. Leon is the only combo-breaker who appears to own clothes in more than one segment of the color wheel.
The Color of Mantra from Asura's Wrath is this depending on the character. The following colors revealed so far are:
Project 0 as per the characters' buttons on the website. Typically prominent on their outfits as well.
Owen, Purple
Aatu, Blue
Bea, Orange
Ciro, Yellow
Kareem, Red
Veronica, White
Noor, Black
Schlock Mercenary gives us an in-universe example, with Lt Shodan's suspicion that a bunch of new recruits charging ahead and blazing away with their guns were prevented from shooting one another only because they were wearing the same color.
Each of the kids in Homestuck has a color that is featured on their clothes, chat log text, etc.: John is blue, Rose is purple, Dave is red, and Jade is green. Interestingly, John and Jade's shirt colors are swapped. This is actually a feature of troll society, where the Fantastic Caste System ranks people by blood color: each of the trolls types with, dresses in, and even wears make up that is the same color as their blood. Karkat, who types in grey to maintain anonymity about his blood, is an exception.
Invoked in Adventurers!, where a (probably ice) dragon painted himself red to make the adventurers think he was a fire dragon, and thus immune to all their fire weaponry. It worked, and they just gave up.
This can be seen in Voodoo Walrus by way of the main cast having certain colors that the artist repeatedly works into their clothes. Orange and green for Grymm, a dull blue and grey for CreepKnight, vibrant blue for Bowler, and purpler for Mirth.
This isn't just for clothes, it extends into their word bubbles as well. And many other supporting characters are color coded too. But some colors change with major personality shifts.
Web Original
In the Global Guardians PBEM Universe, the Iron Legion is a group of seven Powered Armor mercenaries who are code named for the seven spectral colors (Red, Orange, Yellow, Green, Blue, Indigo, and Violet), and whose armors are colored to match their names.
The Lightning Power Special Team, a group of color-coded heroes, are the premiere superheroes of Japan.
Each of the four main characters in Oktober have a color that is associated with them, which makes it easier to keep track of who's entry you are reading. Nick is orange, Natasha is red, Matthias is green, and Smith/Jones is blue. Additionally, side characters seem to have colors that are associated with them as well. Most notably, Daphne is light blue, Midas is blood red or maroon, and Joshua is silver.
The Five Powers of Lambda each have their own particular colours. Soleil is black, Krieggarten is gold, Seisen is blue, Casus Belli is green, and Zafiel is red.
In Elcenia, dragons' colors indicate their magical abilities. In addition to breathing fire of their color, reds gets improved firebreathing and fire resistance, greens get magical empathy, blues are better shapeshifters, violets can breathe underwater, blacks get improved senses, and whites fly better.
Goofy - Green (or Orange, particularly in older works)
Minnie - Pink
Daisy - Purple
Pluto - Yellow
In Avatar The Last Airbender, clothing is color-coded by nation. Air Nomads wear oranges and yellows, Earth Kingdom citizens wear greens and browns, Fire Nation citizens wear reds and blacks, and members of the Southern and Northern Water Tribes wear blues and purples. This also extends to the colors of Team Avatar's members since they're essentially an in-universe Five-Token Band. There are some exceptions; for instance, The Order of the White Lotus consists of citizens from all the different Nations, and they have one type of uniform which, while dark-blue like some Water Tribe clothing, is distinct from any one Nation's style shown in the series.
Mojo was also purple in the one episode when he was given Chemical X powers, and his costume was a darkblue/purple color in general.
Brick, Red
Boomer, Dark Blue-Blue
Butch, Dark Green-Green
Codename: Kids Next Door
Numbuh 1, Red
Numbuh 2, Blue
Numbuh 3, Green
Numbuh 4, Orange
Numbuh 5, Purple/Indigo
G.I. Joe - The good guys shot red laser beams and the bad guys shot blue ones. If a good guy picked up a bad guy's weapon and started firing... it would switch colors.
The villains of the show "Cheat Commandos" from Homestar Runner are actually named Blue Laser.
Wild Kratts: Martin wears blue, Chris wears green. Oh, and Chris's evil Zachbot double wears red.
Voltron is an interesting case as in the original series some of their uniforms didn't match their lion colors and actually matched the lions of someone else. This was changed by Voltron Force th
Keith, Black Lion(but originally had a red uniform)
Lance, Red Lion (but originally had a blue uniform)
Allura, Blue Lion (originally with a pink uniform)
Pidge, Green Lion and uniform
Hunk, Yellow Lion and uniform
The Transformers - Had similar colour-coding for lasers to the G.I. Joe example; Autobots fired orange lasers, while Decepticons fired purple. The Autobots' eyes are blue, the Decepticons' eyes are red (at least in the 80's cartoon.)
And by the way, the entire series is themed around colors, since the special ability of all the Lite Sprites is that they can give various colors to various types of objects, using their wands.
Music
The boyband JLS, who, thanks to their rise to fame on The X Factor, are colour-coded, and have carried it into their music career, often performing with not just in coloured clothing, but having coloured tape around their microphones and coloured earpieces. It's almost guaranteed that if you used their real names (Aston, JB, Marvin and Oritse) very few people would know who you were talking about, but if you said 'the blue/red/green/yellow guy from JLS,' they would.
Supertramp's Album Crime of the Century has this. The lyrics sheet is color coded for each of the two singers. Roger Hodgson is white, and Rick Davies is yellow.
Real Life
This is quite common for any metropolitan mass transit system that's extensive enough to have multiple lines, although it's a toss-up whether the residents of a particular city call the lines by their colors or their actual names (assuming they have other names; some just pick a colour and use that as the name).
The "Hanky Code," a series of signals supposedly used to indicate kink and gender preferences in bars. The color of the hanky indicates the activity and the position of the hanky (left or right back pocket) indicates a dominant or submissive.
Many screwdriver or plier sets have the handles color-coded by tool type (for example, all flathead screwdrivers will have yellow handles while all Phillips heads will be blue) so that you can tell what type of tool it is at a glance.
The PC99 standard gave us the color-coded ports and plugs we all use today to tell the difference between identical plugs that go into identical sockets with different uses (e.g. headphone & microphone jacks, old PS/2 keyboards & mice, etc.).
Similarly, electronic components are color coded so electricians can tell their power and tolerances at a glance.
In Elizabethan England, the actors on stage were color coded- rather than wear costumes fitting the era/location the play was said to take place in, modern-day outfits of different colors were used to tell whether a person was a ghost, wealthy man, etc. This made it easier for less-educated people to understand what was going on.
Pre-Communist political offices were identifiable by color, the pattern on their uniform, and the fanciness of their Nice Hats.
National Colors, usually seen on flags.
Worth mentioning that not always national colours are same as flag colours and some countries may consist of more than one historical nation / land, thus having more than one set of colours. Oh, right, and some change their national colours overtime, though it is less usual now.
Most sports teams have one or two colors associated with their logos/jerseys. In international competitions (World Cup, Olympics) it almost always overlaps with National Colors.
In soccer matches however this is oftentimes subverted. Italy for example plays in all blue, although Italys National Colors are Green-White-Red. Germanys classic dress is white shirt, black shorts, white socks, whereas the National Colors are Black-Red-Gold.
Many military forces will have particular colors they are associated with (for instance, the Red coats that the British army wore for some time). In modern times, said colors can distinguish between branches of a nation's military, or in some cases, smaller branches within those branches*
the United States Army, for instance, has certain color-coded bits on their service uniforms to distinguish members of the different corps, for example, the Military Police Corps wears green and gold, while the Signal Corps wears red and white.
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In 1940, when the risk of a German invasion was at very high, the Irish army switched their uniform color and helmet style (which at the time were similar to Germany's) to emulate Britain's, so they would be readily identifiable as allies from a distance by British soldiers.
Russians With Rusting Rocketstakes it to eleven 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 Bad Ass and marines are even more badass, so when after World War II 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.
Sailors: Dark blue stripes
Naval Infantry: Black stripes
Airborne troops (VDV): Light blue stripes
Border guards: Green stripes
Ministry of Interior (MVD): Red stripes
Emergency Control Ministry (Emercom): Orange stripes
Soldiers do not wear a striped telnyashka—their undershirts are white.
Cigarette packaging tends to follow a general color-coding scheme, although it's far from universal. About the only thing that's consistent across most brands is that if it's in a green or predominently green pack, it's menthol.
Red = full flavor
gold or blue = lights
silver or white = ultra lights
green = menthols
On military ships, the colors of pipes indicate their contents
red = fire main (sprinklers/fire hose)
blue = potable water
yellow = fuel oil/gasoline
green = salt water
Artificial flavoring in the U.S. tends to follow a set pattern somewhere between this and Tastes Like Purple for things that are flavored, such as Popsicles, fruit drinks, or candy.
Yellow = Lemon, or less frequently, Banana (Occasionally Pineapple)
Green = Lime or Mint, very occasionally used for Apple.
Blue = Blueberry or Blue Raspberry.
Purple = Grape
White = Pineapple, Coconut
Fruits change colour depending on how ripe they are. This is thought to be why humans evolved colour vision in the first place. Additionally, recent studies have shown that women see far more different shades of color than men (where a man will see "beige," women will see beige, tan, bone, ecru, and several other shades that men don't.) 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.
Some types of medication particularly thise that are to be taken on an on-again/off-again schedule like some birth control pills. It's easier for the person to take a pill every day than to try to remember how many days they have already skipped/still need to skip so the meds are packaged with placebos for the skip week; those pills are a different color to the actual pill.
Most stars:
O-type stars= blue
B-type stars= bluish-white
A-type stars= white
F-type stars= yellowish-white
G-type stars= yellow
K-type stars= orange
M-type stars= red
brown dwarfs= maroon
neutron stars= purple
black holes= black
Horse racing:
1= red
2= white
3= blue
4= yellow
5= green
6= black
7= orange
8= pink
9= turquoise
10= purple
11= gray
12= lime
13= brown
14= maroon
Some high schools colour code the uniform shirts based on student's ages [1]. See also the Degrassi example above.
Many street gangs have one or more colors associated with that particular gang. For example, the Crips are blue and black, the Bloods are red and black. This can lead to hilarity of the deadly type for people who wander into gang territory wearing a rival gang's colors, intentionally or not.
