My research institute, Institut de Ciencies Fotoniques, tinkers a lot with light. One of the many ways to describe light is through its wavelength.
A laser is a readily available light source which has a well-defined wavelength. The picture below is from my experimental setup. Light coming from a Helium-Neon laser scatters while I focus and made it pass through a tiny hole.
The wavelength of light that an object scatters and the nature of the scatterer, as well as the perception of our eyes and manipulation of the signal from our eyes by our brain (where contextual clues embedded in us by our environment and culture are put into mix), give rise to the color sensation that we feel.
The floors and the laboratory rooms in my work place are color coded. One can follow labels and arrows, placed conspicuously so that no one will get lost (provided of course that you are not an absent minded scientist). I get lost often. These ones are by the stairs.
I inhabit one of the offices in the green floor and I perform experiments in one of the cyan laboratory. At least, my brain knows what green and cyan are. However, I usually end up in the wrong office door. But that’s a different story.