I learned FM Synthesis in a Yamaha class. (Patreon)

I think it was around the time that Reface DX, Yamaha's 4-operator FM synthesizer, was released.

I attended a lecture organized by Yamaha to learn about FM synthesis.

Half of it was studying physics.

Things like the natural frequencies of structures, how FM changes harmonics, what negative frequencies mean, and how to use envelopes to change tones.

However, contrary to Yamaha's intention, FM synthesis these days is more often used to create harmonics of non-integer multiples.

Percussive sounds with FM are a big favorite of mine.