Name: Jazz Theory Explained in 20 Minutes
Uploaded: 2026-03-07T17:24:35.000Z
Duration: 19 min 48 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

So in today's video, I'm going to attempt the unthinkable.

I'm going to try to explain jazz theory in one video.

So I've broken this lesson into three sections.

First of all, chords, then chord progressions, and last of all, scales.

So these are three of the main topics in jazz theory.

These are the main topics which cause a lot of confusion.

So by the end of this lesson, you're going to walk away with a deeper confidence in your understanding of jazz.

Now, we've got a lot to cover, so we're going to get straight in.

So, first of all, let's talk about jazz chords.

Now, chords in jazz go a lot higher than in other styles of music.

So in most styles of music, you'll only encounter three note chords.

So you'll play the root, the third and the fifth, and

you can get different types of chord within just these three notes.

So you can get a major chord, a minor chord, an augmented chord and a diminished chord.

However, in jazz, we build this stack of thirds higher.

So instead of just stopping at the fifth, we'll go up and add another third above the fifth, which gives us the seventh.

And all of these numbers are numbered from the root of the chord.

So if this is a C chord, then this is one.

And that's why all chord extensions are generally odd numbers, because they're built in thirds, which means we're skipping every other note.

Then we can go up to the 9th, we can even go up to the 11th, and

And 13 is pretty much the biggest number you'll see in a chord, because if you go up a third from 13, then you come back to the root.

It's always seventh chords, ninth chords, 11th chords, and 13th chords.

So now let's get specific and look at the actual types of seventh chord.

There's different types of seventh chord.

They have a root, third, fifth and seventh.

But we can create different types of seventh chord by making different combinations of the major third and the minor third.

So we're going to go through the three main seventh chords to begin with.

First of all, we have a major seven chord.

So if you just imagine the notes of C major scale, and

you just play the root, third, fifth and seventh, then you get a major seven chord.

Next let's look at the minor seven chord.

And if you just imagine a minor scale, C minor scale, and

you just play the root, third, fifth and seventh of that scale, well, you end up playing a minor 7 chord.

And next we have the dominant 7 chord here is C dominant 7.

So it's basically a major triad, but with a minor seventh.

So those are the three most common types of seventh chord in jazz.

I would say about 90% of jazz music is built of just these three seventh chords.

Again, the major seven chord, the minor seven chord, and the dominant seven chord.

And they're all just different combinations of major thirds and minor thirds.

Now, above any type of seventh chord, you can add what's known as chord extensions.

And These are the 9th, the 11th, and 13th, which we mentioned just a moment ago.

So for the chord below, the root, third, fifth and seventh are known as chordal tones, chord tones.

The root, third, fifth and seventh, whatever type of chord it is, minor seven, dominant seven, etc.

But above these, you can add a chord extension like the 9th, the 11th, or the 13th, or all three.

You get all sorts of big chords like this.

So how do you find the 9th, the 11th and the 13th?

Well, regardless of what type of chord it is, whether It's a major 7 chord, minor 7 chord, or a dominant 7 chord, the chord extensions are always built from the major scale.

So you imagine a major scale from the root of the chord.

We're just going to imagine a major scale starting from the root, and

you're going to find the chord extensions based on that major scale.

So the 9th is really the same note as the two of the scales, the 1, 2, the 11th is the same as the 4 4th.

And the 13th is the same as the 6th, which is 5, 6.

So even if it's a minor 7 chord, let's take a C minor 7 chord here.

If it tells you to add a 9th, 11th or 13th, you would still imagine C major scale.

To find those notes, it's going to be the same 9th, the same 11th, and

the same 13th as if it was a major 7 chord or a dominant 7 chord.

This is the natural 9th, the natural 11th, and the natural 13th.

And they're all built from the major scale.

Now, the extended harmony notes can also be altered, which means they can be sharpened or flattened.

Sometimes you'll see flat 9, sharp 9 you'll see sharp 11 and sometimes you'll see flat 13.

So how do you find an altered chord extension?

Well, let's say the chord symbol says C dominant 7, flat 9.

Well, we're going to start by finding the natural extension first and we just imagine the major scale.

So C major scale is going to be D natural, and

then you flatten it and that's your chord extension, that's the flat nine.

Or if it said sharp nine again, you find the natural nine first and then sharpen it.

Or if it said C7 sharp 11, we find the natural 11 first.

So run up the major scale to the fourth, which is the 11th, and then sharpen it.

And the same if it was the 13th, C dominant 7, flat 13.

Let's say find the natural 13 first by running up the major scale and then flatten it.

That's where you get these nice chords with altered extensions.

Things like the flat 9, sharp 9, sharp 11 and flat 13.

Now, before we move on to the next topic, I've actually notated a chord symbol reference guide for you.

You can download that for free at the link below and you'll get my one page sheet where I've just notated all of the common types of 7th chord, 9th, CH, 11th chord and 13th chord.

So there's many different ways that you can play any chord in jazz.

So if we just take a look at the seventh chords, the C major seventh chord, which we've looked at.

So if you imagine a group of singers were singing this, well, each note is a voice, a separate voice.

And we can redistribute these voices and turn them upside down and add a few notes in and do all sorts of things to create different voicings.

So just to demonstrate, we can play this, which is a literal voicing, you're playing literally what the chord symbol says, then there's more sophisticated voicings like fourth voicings.

It's just a stack of fourths using notes from C major scale.

We also have fifth voicings where we're using mostly fifths.

And this is still considered a voicing for C major 7.

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Jazz Theory Explained in 20 Minutes

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