(last updated july 16th 2023) everything is a vibration Similar to how our physical reality is composed of molecules, which are composed of atoms, and sub-atomic particles, every sound is created by a multitude of sounds. In every sound, an infinity of sounds. All these particles of sound forms what is called the harmonics. From the root tone of the sound we hear, you have a few major, more subtle notes like echoes of its sources. The octave, the fifth, the fourth and the third are your primary harmonics and how moderm music is formated. The sine wave is pure, withouth harmonics, like the atoms of sound. With a multitude of pure sine wave you can re-create all the sound in existence, and more. The harmonics are important to understand as everything musical come from that source of how sound is created. Harmonics are also quite useful when it comes to creating sound on a synth.