To write a really good chord progression, there are different techniques you can use as a songwriter. Certain tricks, like using what are called “substitute chords” to take a sort of plain-sounding progression to the next level.
This video explains what substitute chords are — and more importantly, where they come from in the circle of fifths:
These images highlight the main points and examples illustrated.
In modern music, the I-V-vi-IV is one of the most common chord progressions. You hear it all the time in many popular songs.
In the key of C, for example, these are chords C-G-Am-F, which come from the C Ionian mode in the circle of fifths.
To alter the sound, you can substitute any of these chords — like replacing V (G) with its relative minor, Em (the iii chord in the key of C). In this way, the iii is a substitute chord for V.
This alternative to the I-V-vi-IV progression is not as common, but makes for some interesting tunes....
The result is a visually complex system of blotches and squiggles that’s confusing and even counterintuitive.
