Learn to Play Augmented Chords
All four basic chord types are built on the same scale degrees, taken straight from the major scale. The difference lies in whether or how we make changes in those notes. Major chords are formed using the root, third, and fifth. A C-major chord, for example, has the notes C (the root), E (the third), and G (the fifth). Lower the third a half step and you get a minor chord—so Cm is C, Eb, and G. If you start with your major chord and raise the fifth by a half step, you’ll get an augmented chord (sometimes designated by a “+” symbol in chord sheets). Using C as an example again, you would make a C-augmented chord by playing C, E, and G#.
Play Example 1 and listen to the differences between a C and Caug chord in open position. You can hear that the augmented chord sounds transitional—it definitely wants to take your ears to another chord. In fact, augmented chords are usually followed by IV or minor VI chords (F and Am, respectively, in the key of C), as demonstrated in Example 2.
Excerpted from Rhythm Guitar Essentials