Most modern western music is based on 12-tone Equal Temperment, where an octave is divided into twelve equally-spaced "steps". It is actually a compromise, so that a harpsichord, piano, glockenspiel, marimba etc could play in any key, equally out-of-tune (if only slightly), something good horn, string, and vocal performers can adjust for automatically (I did not learn this until my last year of college jazz band, and admit I couldn't hear what the director was yelling at me about; sigh).
Here is a Bach guitar piece played on an infinitely-adjustable fretboard guitar; see if you can hear the difference.
I've noted that Henrick, the bass player for The Dirty Loops, plays a bass that has microtonally-adjusted frets, but they're embedded, so (from what I've read) his bass sounds much better in certain keys, but worse in other keys (the human ear is not as finely tuned to pitch in the lower registers, and if its worth the bother, well, I can't hear it personally.)
It's even more fun to recognize that dividing an octave into 12 equally-spaced steps... why twelve? Well, that was arbitrary! African scales were divided into five steps between octaves (not sure if they were equally-spaced,
@rm5 or other trained musicians here can correct me) and early slaves in the US, while trying to play their own music on instruments designed for 12-tone equal temperament, tried to bend certain notes (like the 3rd, and the 7th, downwards) and that gave us... the Blues!
Wendy Carlos released an album in my early twenties where she experimented with different tunings, both twelve-tone, but
not equally-spaced, and scales that were divided into, say, 19 pitches per octave. I listened to that CD a lot, and suddenly could hear where, on pop/rock radio, those standard tunes sounded, well, OUT of tune! Give
Beauty in the Beast a listen, if you want to stretch your ears for fun (while looking up that album title I noted she has released a lot more albums than I realized, and now that I can stream I've got some exploring to do).