To write chord progressions that sound effective, you must have a working knowledge of the most important chords of the key. While the importance of chords varies based on the genre within which one is creating, the most common chords of popular music are as follows:

I chord - the tonic

The tonic chord is the most important chord of any key. It is the “home chord” and carries a sense of stability and finality. Because it is composed of the most stable notes of the key, it does not experience a pull to resolve somewhere else.

V chord - the dominant

The dominant, the second most important chord, creates a sense of tension, climax, or questioning. It carries a strong pull to resolve to the tonic chord.

IV chord - the predominant

The IV chord is a stable chord in relation to the tonic. It communicates a sense of exploration, openness, and stability, and calm movement away from the home chord. We call chords like this “predominant" chords.

vi chord - the minor version of the tonic

The vi chord is the only minor chord of the four. Because it shares two notes with both the tonic and IV chords, its function overlaps with both. It communicates a feeling of gravity, melancholy, or reflection.

Twenty-four unique progressions can be created from these four chords without repeating. These progressions are failsafe, and each one sounds stable and musically coherent.