Use the scroll wheel or swipe up and down to navigate through the harmonic list. Hold space, and click or drag to play the harmonic notes or strum multiple together. I know it's not very high quality and a bit laggy sometimes, so try this link for a smoother experience: https://turbowarp.org/1206027804?fps=60&hqpen
This is a little experiment accurately calculating the aspects of the harmonic series: the series of musical frequencies in which the frequencies are integer multiples of the base frequency (which here is set to C for now). This creates natural sounding intervals and perfectly harmonious chords as opposed to the equal tuning system used on most instruments today (12 TET). For more on the harmonic series: https://en.wikipedia.org/wiki/Harmonic_series_(music) For more about cents and deviations: https://en.wikipedia.org/wiki/Cent_(music)