Each complex sound is made of a different composition of harmonics. Taking the frequency of a fundamental note and its multiples, the different proportions of each multiple (the partials) confer a unique timbre to the sound:
A sound poor in higher partials will be "purer" like the one of a recorder or flute.
A sound rich in higher partials (but skipping the more dissonant ones) will feel more layered and refined, like the violin.
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