What are colours?

What is colour? Just different wavelengths of light...mental (Wikipedia)
Visible light (NASA)
The visible spectrum (Wikipedia)
What is electromagnetic radiation? (livescience)
Spectral colours (HyperPhysics, Georgia State University)
What wavelength goes with a colour? (NASA)
Rabbit & Spaghetti Shiraz (Naked Wines)
This is your brain on nature (National Geographic)
Your colour red could really be my blue (livescience)
How my friends described colours to me when I couldn't see (li.st)
How colours get their names (livescience)
Colour vision in humans & other species (Wikipedia)
A nice overview on rods & cones (HyperPhysics, Georgia State University)
How do we see colour? (livescience)
Photoreceptor cells (Wikipedia)
Bayer filter mosaics: How red, green & blue is arranged on our screens to complement our colour vision (Wikipedia)
Theory of colours (Wikipedia)
Newton & the colour spectrum (Web Exhibits)
Newton's theory of light: His experiment split white light through a prism to make a rainbow, then recombined it through another prism to make white light again (The Star Garden)
Michelangelo Merisi da Caravaggio (Caravaggio Foundation)
Dark Side of the Moon, Pink Floyd (Ultimate Classic Rock)
Red light is just a photon of a certain energy: The wavelength of red light is 650 nm, blue is 475 nm & green is 510 nm (Montgomery Blair High School)
Can you hear colour? Some people with 'synesthesia' claim to be able to (livescience)
What is synesthesia? (Scientific American)
Human ears respond to frequencies of sound between about 20 Hz to 20,000 Hz (Wikipedia)
Human eyes respond to wavelengths of light between about 390 nm to 700 nm (Wikipedia)
What is infrared light? It's just below (longer than) the wavelength of visible red light, so humans can't see it (Wikipedia)
Infrared waves (NASA)
Night vision goggles 'extend' your vision into the infrared (Wikipedia)
Humans give off infrared radiation (Science Questions With Surprising Answers)
The longest waves are 'radio waves', further along than infrared - they're still photons of energy, we just can't see them (livescience)
Radio waves (NASA)
Shorter waves than blue are 'ultraviolet' (UV), they're at a shorter wavelength/higher energy than we can see (NASA)
What is ultraviolet light? (livescience)
Do rainbows have ultraviolet bands & infrared bands? (Physics StackExchange)
Shorter waves than UV are X-rays, they're at a shorter wavelength/higher energy than we can see (NASA)
The shortest waves are 'gamma waves', they're still photons of energy, we just can't see them (NASA)
We need different types of telescopes to 'see' the different types of waves in the universe: radio, infrared, visible, X-ray, gamma (NASA)
Mantis shrimps & bees can see UV light (Catalyst)
The absorption spectrum of water: There's an interesting dip right at the wavelengths of visible light (Wikipedia)
The absorption spectrum of water (London Southbank University)
Transparency of water in the visible range (HyperPhysics, Georgia State University)
Some creatures are 'pentachromats', i.e. they have 5 different types of colour receptors in their eyes (Wikipedia)
What is melanopsin? (Wikipedia)
Melanopsin probably evolved ~1 billion years prior to cone cells: These receptors independently gauge the amount of blue or yellow incoming light & route this information to parts of the brain involved in emotions & the regulation of the circadian rhythm (livescience)
Someone who is colour blind is missing 1 or more of the 3 sets of colour-sensing cones (Wikipedia)
How we see colours: Light absorption, reflection & transmission (the Physics Classroom)
Sunderland claims the first stained glass in England (BBC, Radio 4)
Sunderland National Glass Centre
Visible light & the eye's response (the Physics Classroom)
You can't mix all the colours & get white paint (Reference)
Why does mixing every paint colour produce grey not white? (Physics StackExchange)
White light is