Common Tone

This refers to using the same note in successive chords. This creates a relationship that links all the chords together. For example, in a progression consisting of Em7, C9, and Am11, the note “D” is contained in all of those chords. It is the flat seventh of Em7, the ninth of C9, and the 11th of Am11. Coincidentally, the note “E” is also contained in all three chords — the root of Em7, the third of C9, and the fifth of Am11. Having those two common tones among the chords can help create very smooth voice leading when playing the progression and provides powerful source material for crafting solos as well.