Harmonics and Pitch

Waveforms that contain more than one frequency component (i.e. aren't purely sinusoidal) may still be periodic.

If frequency components are (more or less) integer multiples of some fundamental frequency $f_0$, producing a spectrum with (more or less) evenly spaced frequency components, they are called harmonics.

Signals with harmonic spectra have a periodic waveform where the period is the inverse of the fundamental frequency (often the sounding frequency).

Pitch is our subjective response to a fundamental frequency within the audio range.

The harmonics contribute to the timbre or quality of a sound, but do not necessarily alter the pitch.