The guitar chords on this page are built from the C major scale. The C major scale has 7 scale steps. They are the notes C,D,E,F,G,A,B.

The Cmaj9 Chord

A dominant ninth is a dominant chord with a ninth (the ninth would be the same note as the 2nd: D). A ninth chord, as an extended chord, typically includes the seventh along with the basic triad structure. Thus, a Cmaj9 consists of C E G B and D.

The C9 Chord

When the symbol “9” is not preceded by the word “major” or “maj”, the implied seventh is a minor seventh.

C9 consists of C E G B­ and D  and would usually be expected to resolve into the  F major chord.

F is the implied key because of usual role of the dominant.  C is the dominant of F.

The Cm9 Chord

The minor ninth chord is played with the third and seventh both flattened. The formula is 1, ­3, 5, ­7, 9. This chord is written as Cm9. This chord has a more “bluesy” sound and fits very well with the dominant 9th.

The C Added Ninth Chord

An added ninth chord is a major triad with an added ninth. Cadd9 consists of C E G and D. The 9th scale step is actually the same note as the 2nd scale step. In this case the 2nd/9th is D.  Added ninth chords are different from other ninth chords because the seventh is not included.