An arpeggio is a type of broken chord in which the notes that compose a chord are individually sounded in a progressive rising or descending order. The word "arpeggio" comes from the Italian word "arpeggiare," which means to play on a harp. Arpeggios enable composers writing for monophonic instruments that play one note at a time (such as the trumpet) to voice chords and chord progressions in musical pieces. Arpeggios are also used to help create rhythmic interest or as melodic ornamentation in the lead or accompaniment. Though the notes of an arpeggio are not sounded simultaneously, listeners may effectively hear the sequence of notes as forming a chord if played in quick succession. When an arpeggio also contains passing tones that are not part of the chord, certain music theorists may analyze the same musical excerpt differently.

Arpeggios are commonly used in many music genres and are particularly highlighted in genres with significant focus on melody and ornamentation, such as flamenco and neo-classical. Arpeggios are an important part of jazz improvisation. On guitar, sweep-picking is a technique used for rapid arpeggiation, which is most often found in rock music and heavy metal music.

Arpeggios are also used as a form of basic technical exercise that students use to develop intonation and technique.