Microtonal music is music that uses sounds that are not the regular notes you normally hear in music like "do, re, mi, fa, sol, la, ti, do." Instead, microtonal music uses notes that are in between these regular notes or completely different notes altogether.
Imagine you have a piano with 88 keys, and each key is a different note. Regular music only uses these 88 keys, but microtonal music uses the spaces in between these keys. It’s like having a secret 89th key that nobody else knows about or using all 88 keys to play notes you’ve never heard before.
It’s like when you play a video game, and you only have a joystick with four directions that make your character move up, down, left, or right. But imagine there's a secret button that makes your character move diagonally, and only a few people know about it. Microtonal music is like using that secret button to unlock new sounds in music that most people don't know about.
Some musicians like to create their own microtonal instruments. They might make a guitar with extra frets or create a keyboard with more keys than usual, so that they can play these different notes.
Overall, microtonal music is music that uses sounds that are not commonly found in regular music, and opens up a whole new world of musical possibilities.