In music, harmonics refer to the overtones or partials that are produced when a musical instrument is played. When a note is played on an instrument, it produces a fundamental frequency that corresponds to the pitch of the note. However, this fundamental frequency is not the only sound produced. The instrument also produces higher frequencies called overtones, which are multiples of the fundamental frequency.

These overtones or harmonics contribute to the timbre or tone quality of the sound produced by the instrument. They create the unique sound of different instruments and can be manipulated by musicians to create a wide range of sounds and effects.

Harmonics can also refer to a specific technique used by some string players, particularly on the guitar and other fretted instruments. When playing a note, the player lightly touches the string at certain points along the string length, creating a harmonic overtone. This technique is used to create a bell-like sound or to play notes that are not otherwise available on the instrument. It is commonly used in classical and acoustic guitar playing, as well as in other genres of music.