Depending on which instrument you play, there's a good chance you've been playing chords from nearly the very beginning... and even if you haven't you probably have an intuitive sense of what a chord is. HOWEVER: lets make sure we're on the same page.

A chord is any three or more notes played at the same time. If we want to get really technical, there might be some nuance there, but lets save that for later. As far as we're concerned chords are just multiple notes played together.

The most basic building-block type of chord is a triad. Very likely the first chords you learned on your instrument, if you play an instrument that can play chords, were triads -- the basic major and minor chords we all know and love are triads. (again, there's some nuance here that we'll get into later, but for the moment lets not overthink this stuff)

Compared to some of the other foundational stuff we've covered so far, this concept should come pretty easily. There will be plenty of practice to be had internalizing all of this, but the concept itself is pretty straightforward!

Let's go!

Pick any note. Go up a third. Go up another third. You have a triad.

Starting on D: D — F — A

Starting on G: G — B — D

Starting on E: E — G — B

That's it. Root, third, fifth. The bottom note is the root (the note the chord is named after), the middle note is the third, and the top note is the fifth. The third and fifth are named for their interval above the root.

Not all triads sound the same. The quality of a triad depends on what kind of thirds you're stacking.

A major triad is a major third on the bottom and a minor third on top:

• Root to third: major third (4 half steps)
• Third to fifth: minor third (3 half steps)
• Root to fifth: perfect fifth (7 half steps)

D major: D — F# — A. D to F# is 4 half steps (major third). F# to A is 3 half steps (minor third). D to A is 7 half steps (perfect fifth).

Major triads sound stable, bright, resolved. When someone plays a "D chord" with no other qualifier, they mean D major.

Flip the stack. A minor triad is a minor third on the bottom and a major third on top:

• Root to third: minor third (3 half steps)
• Third to fifth: major third (4 half steps)
• Root to fifth: perfect fifth (7 half steps)

D minor: D — F — A. D to F is 3 half steps (minor third). F to A is 4 half steps (major third). D to A is still a perfect fifth.

The only difference between a major and minor triad is the third. The root and fifth stay the same. That one note, one half step, is the entire difference between bright and dark.

Here's every triad you get from the notes of C major, built by stacking thirds from each scale degree. These are called diatonic triads — "diatonic" just means "built from the notes of the key." You'll see this word a lot from here on out.

Three are major (C, F, G), three are minor (Dm, Em, Am), and one is something else — B-D-F doesn't have a perfect fifth. B to F is only 6 half steps. That's a diminished triad, and we'll get to it in a moment.

This pattern — major, minor, minor, major, major, minor, diminished — is the same in every major key. The chord types are baked into the scale itself.

If you play guitar or banjo or some other strummy kind of instrument, you've probably been playing chords forever, but maybe you haven't stopped to consider what the notes are IN those chords. WELL NOW YOU KNOW (for the major and minor chords anyway, we'll talk about everything else soon enough). Take some time to play through those common chord shapes and think about the notes you're playing. They might not come in the same order as the triads we've been building.. but that G Major chord you learned a long time ago has a combination of Gs Bs and Ds!

Major and minor triads both have a perfect fifth from root to top. A diminished triad doesn't. It's two minor thirds stacked on top of each other:

• Root to third: minor third (3 half steps)
• Third to fifth: minor third (3 half steps)
• Root to fifth: diminished fifth (6 half steps — the tritone)

B diminished: B — D — F. B to D is 3 half steps. D to F is 3 half steps. B to F is 6 half steps — that's the tritone we talked about in the intervals lesson.

Diminished triads sound tense and unstable, like they need to go somewhere. You won't use them as often as major or minor, but they show up naturally in every major key (on the 7th degree, as we just saw) so you will run into them.

One more. An augmented triad is the opposite of diminished: two major thirds stacked on each other.

• Root to third: major third (4 half steps)
• Third to fifth: major third (4 half steps)
• Root to fifth: augmented fifth (8 half steps)

C augmented: C — E — G#. C to E is 4 half steps. E to G# is 4 half steps. C to G# is 8 half steps — one half step wider than a perfect fifth.

Augmented triads sound eerie and unresolved. They don't show up in the diatonic triads of a major key (unlike diminished, which gets one slot), so they're less common. But they're out there, and you should be able to recognize one when you hear it.

Triad	Bottom third	Top third	Outer interval
Major	Major 3rd (4)	Minor 3rd (3)	Perfect 5th (7)
Minor	Minor 3rd (3)	Major 3rd (4)	Perfect 5th (7)
Diminished	Minor 3rd (3)	Minor 3rd (3)	Diminished 5th (6)
Augmented	Major 3rd (4)	Major 3rd (4)	Augmented 5th (8)

Major and minor are the ones you'll see constantly. Diminished and augmented are rarer, but when they show up you should know what you're looking at.

• Odd Quartet — How Chords Work — covers all four triad types plus a preview of inversions that we'll get to in an upcoming lesson.

• Jesse Strickland - Augmented and Diminished Chords - Very quick little video that talks a little more about Augmented and Diminished triads.

• Synthet - the crunchiest chord - A super fun video about diminished chords. (also, starts talking about seventh chords 😱 never fear, we'll get to those soon!)

• musictheory.net - Diatonic Triads - simple interactive explainer.

• Open Music Theory - Triads - this one goes a little farther and talks about how these triads relate to chord symbols you might already be familiar with on your instrument.

Play these on your instrument. Build major and minor triads starting on every natural note, then try a few with sharps and flats. Say the note names out loud as you play them.

Try this... it may be difficult! Our next lesson is about making this a little easier to recognize on the fly, but for now take your time, feel free to scroll back through this lesson and the linked resources if you need to, and don't beat yourself up if it seems too hard!

If you're getting most of these right, great. If not, don't just move on and hope it clicks later. The Note Trainer has a chord mode that lets you drill triads at your own pace, and the next lesson has targeted exercises for the specific skill that makes triad identification fast. Spend time with this stuff. Everything we build from here (seventh chords, chord progressions, harmony) assumes you can look at a triad and know what it is without much effort.