What is the relationship between funamental frequency and it's harmonics in a harmonic series?

In a harmonic series, the fundamental frequency is the lowest frequency of a waveform, and its harmonics are integer multiples of this frequency. Specifically, the first harmonic is the fundamental frequency itself, while the second harmonic is twice the fundamental frequency, the third harmonic is three times it, and so on. This relationship creates a series of frequencies that are integral multiples of the fundamental, resulting in a richer sound when produced together. The presence of these harmonics is essential for defining the timbre of Musical Instruments and voices.