Yellow is a primary colour, along with red and blue. The word yellow comes from the Old English word geolu.
In Japan, yellow is the colour of courage.
In Egypt, it is the colour of mourning.
In American slang, a coward can be said to be yellow or yellow-bellied.
Yellow is a colour that is easily visible, this is why it is commonly used to indicate caution, for example, on a set of traffic lights, yellow divides the red light and green light, meaning drivers can go, but be cautious.
In some countries, taxi's are commonly yellow. This practice began in Chicago, where taxi entrepreneur John D. Hertz painted his taxi's yellow based on a University of Chicago study alleging that yellow is the color most easily seen at a distance. This idea has also been used with school buses and road warning signs.
Yellow is an appropriate colour for a room used for studying because it has a stimulating effect on the mind.
There is a type of woodpecker called the Yellow-shafted Flicker (Colaptes auratus). They have yellow shafts on their wing and tail feathers – also they have a rather funny name :)
Yellowtail is the general name for loads of different species of fish that have yellow tails or a yellow body.
Goldenrod is a yellow flowering plant in the Family Asteraceae. Also a city in the Poékmon world!
Coldplay achieved worldwide fame with their 2000 single "Yellow". It is a song that associates things the singer sees with the color yellow.
Yellow cards are shown by a referee in football/soccer to indicate that a player has been officially cautioned because they have committed a foul or have wasted time.
Finally, some cool dude called Dan Zambonini asked an interesting question - something that no ordinary mind would even think of:
Why were Post-it Notes originally yellow?
He managed to get an answer from the creators of post-it notes via twitter, here's their answer:
"We were in the labs and if you imagine, this is my lab here, and then there's a corridor, and then there’s another lab. They happened to have some scrap yellow paper – laughs – it's absolutely true."
"They had some scrap yellow paper – that's why they were yellow; and when we went back and said 'hey guys, you got any more scrap yellow paper?' they said 'you want any more go buy it yourself', and that's what we did, and that's why they were yellow."
"To me it was another one of those incredible accidents. It was not thought out; nobody said they'd better be yellow rather than white because they would blend in - it was a pure accident."
So, if you know any more facts about the colour yellow, please leave them in a comment below, thanks!