Chords for Keyboard
The chords in the table besides minor and major triads vary in how common they are in practice, but all are fairly even, so they are still generally useful chords. X7 or X Dom 7 means Dominant Seventh. Just these three chord types (min, Maj, Dom 7) are so common that they comprise perhaps 90% or more of the chords in the music written by The Beatles, for instance. Other useful chords include suspended, (sus), diminished, (dim) and augmented (Aug) chords.