Chord Theory: Triads

Chords sound so nice. They add harmony to a song and provide context for the melody. In popular music, the chord progression — a repeated series of chords — can be the most identifiable part of a song. But what are chords exactly? Read on and find out.

Very simply, chords are two or more notes played at the same time. Most of the time it is three notes played simultaneously. This grouping of three notes is called a triad. You may be thinking, “But wait a minute? I’m a guitar player and most of the chords I know are played on 4, 5 or 6 strings. How does that make sense?” Well, the short answer is that one or more of the notes in the triad have been duplicated into different octaves to create a fuller sound.

So let’s find out where we get these triads. How do we decide which three notes sound good together? Well, the notes are pulled right out of the key — right from the major scale. Here’s how it works:

Write out a major scale across two octaves. In this case, I’ll use the C major scale but you can use any scale:

C  D  E  F  G  A  B  C  D  E  F  G  A  B  C

Now, pick a starting note. That will be the “root” of your chord and thus the name of your chord. I noted mine with a lower-case “r”:

C  D  E  F  G  A  B  C  D  E  F  G  A  B  C

Now, we’re going skip a note and land on the third, which conveniently is called the “third” of the chord:

C  D  E  F  G  A  B  C  D  E  F  G  A  B  C
r     3

From the third, we’re going to skip another note and land on the “fifth” of the chord:

C  D  E  F  G  A  B  C  D  E  F  G  A  B  C
r     3     5

Using this approach, we see that a C chord in the key of C uses the notes C, E and G. The root, third and fifth, respectively. You can do this starting from any note in the scale. For example, let’s see what the B chord looks like:

C  D  E  F  G  A  B  C  D  E  F  G  A  B  C
r     3    5

The B chord — actually, it’s a B diminished chord, but don’t worry about that just yet — in the key of C has the following notes: B, D and F. You can repeat this method from all of the notes in this scale and any other scale. You’ll always end up with a triad. Simple as that.

C  D  E  F  G  A  B  C  D  E  F  G  A  B  C
                  r     3     5

Check out this video to see a clever way of writing the scale to reveal the hidden triads within:

For reference, check out my post on the importance of scales and you’ll see chord diagrams for all of the chords in the key of C. Notice that the C chord has C, E and G notes in it. Check out the B chord too.

In future posts, I’ll talk about all of the varieties of chords.

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