While the notes of a G 7 chord are G–B–D–F, jazz often omits the fifth of the chord-and even the root if playing in a group. For example, if a tune is in the key of C, if there is a G chord, the chord-playing performer usually voices this chord as G 7. In jazz chords and theory, most triads that appear in lead sheets or fake books can have sevenths added to them, using the performer's discretion and ear. Jazz chords are chords, chord voicings and chord symbols that jazz musicians commonly use in composition, improvisation, and harmony. Major seventh chord on C, notated as C Δ7
