You’ve got to admit, the flow between the tonic chord (I) and the dominant chord (V) is nice. And that’s because the movement from one triad to the next is like a short visit with a good friend. But after a while it’s fun to with hang out with other friends, too. So musicians like to mix it up a bit—adding even more chords to their songs.

In music, the next most popular choice is definitely the subdominant chord (IV)—because it’s closely related to both the tonic (I) and dominant (V) in the circle of fifths. Together, these three chords sound great. And since they’re the only major triads in a major scale progression, we can easily hear a special connection between them.

To see what I mean, try moving back and forth between the tonic (I), dominant (V), and subdominant (IV) triads. When they’re played one after another, it’s like music to our ears….

In fact, the flow from one chord to the next is so smooth that musicians sometimes call these triads the “primary chords” of any key. And they show up all the time in music. For example, turn on the radio and listen. Nearly every song in rock, folk, country, jazz, rap, and classical music is based on these three simple chords. It’s amazing!

To see how they work, let’s again look at that classic tune, “Twinkle, Twinkle, Little Star” by Mozart. We already know this song has a great melody. But when we add those three simple chords of C major (I), F major (IV), and G major (V), it totally shines.

Before playing, try moving your left hand between these three chords a few times. That way, your muscles will remember where to move as you make your way through the song. And remember that the less you move your hand, the less likely you’ll be to hit a wrong note. So some of the chords are played as simple inversions.

Don’t worry about taking it one measure at a time. If you make a mistake, just go back and play those notes again—it’s all good. By adding another chord to the mix, we need a little more focus. But the result is worth it. Because the variety is good for our ears and our music stays fresh.

After you’ve rocked out a bit, try playing these same three chords in each key. Like a group of superstars, the tonic (I), subdominant (IV), and dominant (V) chords sound great together. What can I say? The “primary chords” are just cool.