Ed Sheeran successfully defended his copyright court case, what is chord progression and why do so many songs use it?

Question

I watched a video where he demonstrated that many songs use the same tune / Chord progression (?). What is chord progression and why was the one in question essentially uncopyrightable?

In: 531

Answer 1

One of the earliest and most recognizable versions of this chord progression is “Canon in D” by Johann Pachelbel. It was composed in 1680. Being that old, it is no longer subject to copyright laws and is therefore public domain.