Major and minor chord keys use a formula of major chords, minor chords, and a diminished chord.
Guitar Chords in the Key of C Major:
C Dm Em F G Am 
Bdim
The chords in each key are like a family of chords that will sound like they belong together when played in a chord progression.
A chord progression is a pattern of chords, belonging in the same chord key, played in a certain order to form songs. A popular guitar chord progression is the I – IV – V progression.
Guitar Chords in Major and Minor Keys
Guitar Chords in Major & Minor Keys | GuitaristSource.com
Major and minor chord keys use a formula of major chords, minor chords, and a diminished chord.
Guitar Chords in the Key of C Major:
C Dm Em F G Am
Bdim
The chords in each key are like a family of chords that will sound like they belong together when played in a chord progression.
A chord progression is a pattern of chords, belonging in the same chord key, played in a certain order to form songs. A popular guitar chord progression is the I – IV – V progression.
Guitar Chords in Major and Minor Keys