

The table below shows how the C major can be harmonized into four-note chords with the dominant 7th appearing as the V chord: I That is the reason that G7 is common in progression based on the C major key whereas F7 is not. The dominant 7th chord can be found on the fifth degree in the major scale. For example C7 includes the notes C, E, G, Bb whereas the C major scale include the notes C, D, E, F, G, A, B and C minor scale C, D, Eb, F, G, Ab, Bb. This result in a slight dissonant sounding chord.

The dominant seventh doesn't fully correspond to the key of major with the last tone corresponding with the minor scale. This chord category is not to be confused with the major 7th and minor 7th. The x letters and numbers indicate that the string shouldn't be played or on which frets.

The chord names are on top of the pictures.
