Augmented and diminished chords are not as common as major or minor chords, but it is still important to learn them. They occur in many pieces of music as a means of creating tension, before resolving to either a major or minor chord.
Here are some examples demonstrating these chords. Listen to the CD to hear what they sound like.
C+
Co
This example which uses arpeggios of all four types of triads – major, minor, augmented and diminished.