Superimposition, that's the word
Apart from Googling 'superimposition' and so forth, I've just been playing around with harmonics. And when you play the 8th harmonic (or any harmonic for that matter) the string barely moves at all, they're just ripples. This helps me understand how all the harmonics can be on the string at the same time
What I find most amazing is the pickup can read these microscopic movements, all thanks to electromagnetism!
Well I think my question has been answered and I thank you all for your contributions. The other night when I posted this question I didn't think it would go for so long and the more I think about it, the more questions I find. Now its giving me a bit of a headache
Lets us conclude, "IT JUST DOES"