A harmonic series (also overtone series) is the sequence of frequencies, musical tones, or pure tones in which each frequency is an integer multiple of a fundamental.
Harmonics of a vibrating string, showing how the frequency of each harmonic is related to integer multiples of the fundamental frequency f. The location of the nodes (red dots) can be used to define equivalent strings (on the right) with 1/2, 1/3, and 1/4 of the length of the original strings, having the same frequency.
