When a pitch is played, the main note heard is the fundamental (the note itself), but there is also present a series of other pitches above it called overtones or harmonics. The first overtone is an octave above the fundamental, the second is an octave and a fifth above the fundamental, the third is two octaves, the fourth is two octaves and a third, and so on, with each following overtone closer to the last than the last was to the tone before it.

The series of overtones (harmonic series) for the fundamental pitch C would consist of C-C₃-G₃-C₄-E₄ G₄-B-Flat₄*-C₅-D₅ E₅-F-Sharp₅*-G₅-A₅*-B Flat₅*-B₅-C₆.