C Mixolydian

The C Mixolydian mode — C D E F G A Bb — shown across the guitar neck.

Swipe the neck sideways to see the higher frets.

C Mixolydian is the major scale with one note changed — the b7, Bb. That single note is what the mode sounds like; lean on it and the colour is obvious, avoid it and you are just playing major.

The tool shows this from its parent key, F major, with C marked as where Mixolydian begins, the same seven notes centered on F.