An arpeggio is a chord played one note at a time. As it is not possible to sing two notes simultaneously with one voice, singing an arpeggio is the only way a singer can sing a chord. The value of arpeggios is that they enable you to play lines which fit chord progressions perfectly, since every note of an arpeggio is a note of the accompanying chord. The following C major arpeggio consists of the notes C, E and G. These are the root, third and fifth of a C major chord.
For every type of chord there is a corresponding arpeggio. The next example shows a C minor arpeggio which consists of the notes C, Eb and G–the root, flattened third and fifth of a C minor chord.
The following piece consists entirely of notes from minor arpeggios. The chord symbols above the music tell you which arpeggio occurs in any given bar. The chord symbols only change when the chord or arpeggio itself changes.
Arpeggios may occur in inversions just like chords i.e., you don’t have to start an arpeggio with the root note; you could start with the 3rd or 5th of the chord and continue the arpeggio up or down from there. This is demonstrated here with C major and minor arpeggios.
Arpeggios may also extend over more than one octave. An A minor arpeggio spanning four octaves is shown here.