"In these lessons, you'll learn the basics of music making. No prior experience or equipment is required; you'll do everything right here in your browser."
Open Music Theory
Hybrid Pedagogy Publishing
Brian Moseley, Bryn Hughes, Kris Shaffer
"Open Music Theory is an open-source, interactive, online “text”book for college-level music theory courses."
Music Theory (dot) net
Red Bull Music Academy
"In-depth interviews with some of music’s most creative and inspiring minds, spanning two decades and hundreds of artists"
Hancock Institute of Jazz, NYU Music Experience Design Lab
"MathScienceMusic.org is a free toolkit for teachers, bringing together the best resources in math, science and music.
Designed for students, kindergarten through college."
Music | The Pudding
Every Noise at Once
"an ongoing attempt at an algorithmically-generated, readability-adjusted scatter-plot of the musical genre-space, based on data tracked and analyzed for 4,954 genre-shaped distinctions by Spotify as of 2020-10-07"
Below are a few awesome resources for learning about this subject.