More about the fourth chord
Fourth chords have a very open and versatile sound, they create an unpredictable tension that can be resolved in multiple ways. It is created by stacking perfect fourth intervals on top of each other. For instance: C F Bb or G C F. Which would be triads of a fourth chord. These could actually be named C7sus or G7sus (without a fifth) because they already include a minor seventh.
More commonly it is played with another fourth stacked upon the minor seventh. This actually creates an inversion of a minor chord with an 11 (and without a perfect fifth) because the last note will be a minor third compared to the starting note. For example: D G C F or Bb Eb Ab Db.
Usage and play
Because of it's interchangeability it is a very interesting chord which lends itself to blend into many chord-degrees within a key. Playing in a minor key you could actually use it on every degree except the second. For instance in D minor: Dm, F, Gm, Am, Bb and C!
This chord is mostly used in Jazz, Classical and World music. However you might occasionally find it in Pop songs.
