Beginner Acoustic Piano Lessons-Piano Chord Progressions A chord progression is a series of chords put together in a pattern. In the beginning of the video, I play a chord progression in the key of F. That progression is F, B flat, C, B Flat, and back to F. Chord progressions are based around piano scales , so when I say the song is in the key of F, I mean that its chords are based on the F major scale. F is the root of the scale, B flat is the fourth note of the scale and C is the fifth note of the chord. Because of this we can say that F is the I chord, B flat is the IV chord, and C is the V chord. These three chords are the most popular chords in modern music. A lot of the songs you hear on the radio are written with just those three chords, although in a variety of keys.