Visible spectrum (VIS) aka "light"

385 - 789 THz 780 - 380 nm
...is an apperently (1) small band of the EM spectrum, though it is emitted and reflected by almost everything and it is also least absorbed by the atmopshere. Probably this is why evolution decided-make the four cells in the retina of the human eye sensitive-it. One type of cell 'feels' the intensity of light, the other 3 covers Redish, Greenish and Blue-ish intensities (each with it's sensitivity curves) . Hence we can see all colours by a combination of those 3.
R: ~ 625-740 nm / O: ~ 590-625 nm / Y: ~ 565-590 nm / G: ~ 520-565 nm / Cy: ~ 500-520 nm / B: ~ 430-500 nm / V: ~ 380-430 nm

Sources:

Everything

Uses:

Sight: the human eye typically has a maximum sensitivity of ~555 nm (in the green; figures when evolved in nature)
fibre optics, Astronomy
RGB (red green blue) in TV / computers-"fool" our eyes-see all visible colors by adding different saturations of these colors
CYV (Cyan Yellow Violet?) in printers / copiers /painters-do the same thing but by substracting values

Interaction with matter:

Effects:

look around

Interesting notes:

  1. It's a common misconception that light is a very small strip of the spectrum.
    It's often forgotten that we look on a logarithmic scale. When you compare the band to the bands before it lineary, it's actually huge! It' still 135(!) times bigger than the whole radio spectrum and about as big as the radio and infrared spectrum combined. But it's tiny compared to UV or higher, but even more tiny are the lower bands.

    See this (todo) image of the spectrum on two linear scales.
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