How Music Works
Interactive Music Theory Lessons




Why learn basic music theory?

Do you want to be able to make your own music, build your own chord progressions, or even improvise your own melodies? Do you want to skip all the jargon and complicated symbols?

With Lightnote, you'll learn basic music theory the simple way with bite-sized lessons, no confusing notation, and no instruments required!

1

Sound. What is it?

A sound is a wave.

Every sound is created from vibrations in the air.

It can be louder...

Increasing the height of the wave, or amplitude.

...or more quiet.

Decreasing the height of the wave, or amplitude.

It can be lower in pitch...

Lower notes will become longer waves.

...or higher.

And higher pitched notes will be more compressed.

There are infinitely many notes.

Not just the ones you know, like A through G, but everything in between. So how do we pick which notes to use?

2

Harmony
Notes that sound good together.

What makes this sound good?

Play

...and this sound bad?

Play

A simple ratio between the notes means they sound nice together.

Can you see the repeating pattern in the first one? Your ears can hear the simple ratio between these waves.

It turns out that when the waves line up in nice patterns, it sounds good!!! Our ears like it when the ratio between the waves are simple.

For example, three waves of note #1 for every two waves of note #2 is a 3:2 ratio. Now try it for yourself.

Which of these notes do you think will sound nice together?

Click each of the options to see the wave form.

Wave 1
Wave 2
Wave 3

Show Answer »

How about these notes?

Again, which note do you think will sound good with this note. Hover over each of the options to see the wave form.

Wave 1
Wave 2
Wave 3

Show Answer »

3

The Pentatonic Scale
The five-note system that can do no wrong.

A lot of music theory is about limiting which notes to use in your song to a small set that sound good together. The earliest set of such notes was called the Pentatonic Scale. It has five notes and looks like this:

1
2
3
4
5

Click the circles to play the notes.

Note 1

Lets look at each of these notes and their waveforms.

Play


One of the most important things to understand is that the notes themselves aren't important. You could start the pentatonic scale on any frequency. In this case, Note 1 has a frequency of 200Hz, but it could be any other number as well.

What is important is the ratio the other notes have with Note 1. Lets take a look.

Note 4

For Note 4 we have a very simple ratio of 3:2. That is, for every two waves of Note 1 (200Hz) there are three of Note 4 (300Hz). Click play to hear how nice they sound together.

Play

Note 3

The next ratio used is 5:4. Note 3 has a frequency of 250Hz. You can see that for every four waves of Note 1 there are five of the Note 3.

Play

Note 5

The next ratio used is 5:3 to give us 333.3Hz. You can see that for every three waves of Note 1 there are five of Note 5.

Play

Note 2

Lastly is Note 2 with a ratio of 9:8 (225Hz). You can see that for every eight of Note 1 there are nine of Note 2.

You might have noticed that this ratio isn't as simple and therefore these two notes don't sound as nice together as some of the previous notes.

Play

Octaves

Finally, lets find a pair of notes with the simplest ratio, 2:1. This is known as an Octave and is not considered a new note. An Octave is the same note with a higher pitch. In this case 400Hz and 200Hz.

Play
4

The Chromatic Scale

The Pentatonic Scale (below) that we just covered is limiting in a lot of ways. The notes are not consistently spaced and there are so few of them. Modern music demands a more flexible system.

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5
8
10

Thus the Chromatic Scale was born. This system added 7 more notes to fill in the gaps while still including all the notes from the Pentatonic Scale. Click to hear the notes.

1
2
3
4
5
6
7
8
9
10
11
12
1

Almost all modern instruments are built to this system, including guitars, keyboards, woodwinds, etc. For example, see how the keys of the piano below match up to the 12-note system.


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2
3
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5
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7
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9
10
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12
1
2
3
4
5

Naming the Notes

At this point we've only been labeling the notes 1 through 12. It's time to show you their real names.

Unfortunately, I truly believe that the naming of the notes is why music theory is so difficult. If I could go back in time, I would not name the notes this way. But since it's what we've been using for thousands of years, there's no real way around it. Here they are:

C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C

Let's point out some poor qualities about this:

  • We use 7 letters to describe 12 notes.
  • There are sharps (#) each of which can also be called a flat (♭).
  • Not all the notes have sharps or flats.
  • The natural letters will play a C Major scale, but only when you start on C.

Equal Temperament

This 12-note system has a lot of nice properties. The first is Equal Temperament. This means that the interval between any two adjacent notes is exactly the same.

Why is this useful? Well it means we can start a melody on any note.

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3
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5
6
7
8
9
10
11
12
1
Play
1
2
3
4
5
6
7
8
9
10
11
12
1
Play

Too many notes

A downside to having all of these notes is that not all of them sound good together, making this system less forgiving than the Pentatonic Scale. Lets listen to some that don't sound so nice.

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2
3
4
5
6
7
8
9
10
11
12
1
Play
5

Chords
A group of notes that sound good together.

Here we'll take a look at three of the most common chords: Major, Minor, and Diminished. These are all known as Triads, simply a chord with three notes.

Major Chord

The Major Chord is the most common chord. Whenever you're asked to play a chord without specifying what type, then it's a Major chord. (For example, D Chord = D Major Chord).

  • Start with any note. This is the first note in the chord.
  • For the second note, count up four notes.
  • For the third note, count up three more notes.
  • The chord is named after the first note.

Click any note to see its Major Chord.

C Major Chord

C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
0
1
2
3
4
5
6
7

Minor Chord

The Minor Chord is similar to the Major Chord except that the second note is one lower:

  • Start with any note. This is the first note in the chord.
  • For the second note, count up three notes.
  • For the third note, count up four more notes.
  • The chord is named after the first note.

Click a note to see its Minor Chord.

C Minor Chord

C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
0
1
2
3
4
5
6
7

Diminished Chord

The Diminished Chord is a less common chord where the third note is one lower than the Minor chord's third note.

  • Start with any note. This is the first note in the chord.
  • For the second note, count up three notes.
  • For the third note, count up three more notes.
  • The chord is named after the first note.

Click a note to see its Diminished Chord.

C Diminished Chord

C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
0
1
2
3
4
5
6
6

Keys
A group of notes used in a song.

Because not all of the 12 notes sound good together, we must select a set of notes to use in a song. This is a Key.

When a song says that it is in the key of C Major or D Minor this is simply telling you which of the 12 notes are used in this song.

That's it.

Major Key

Seven notes from the Chromatic Scale. The 1st, 3rd, 5th, 6th, 8th, 10th, and 12th intervals. It then repeats back from 1. This is one of the most common keys in music. Click the notes to play them.

C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C

Remember, the frequency of the starting note doesn't matter. The Major scale will always have these intervals.

Minor Key

Again, seven notes from the Chromatic Scale. The 1st, 3rd, 4th, 6th, 8th, 9th, and 11th intervals. It then repeats back from 1. This is also a very common Key.

C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C

There are many other keys, but these two are the most common. We'll save the other keys for a later lesson.

The Key Tool

Here's a little tool to help you find the notes in any Key. Notice how the pattern never changes. Instead we just shift where we begin our Key pattern.

C Major Key

C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
A
A#
B
C
C#
D
D#
E
F
F#
G
G#
Major
Minor
7

Diatonic Chords
Chords that fit in a particular Key.

So far we've learned that:

  • a Key is a collection of notes used in a song
  • a Chord is a set of notes, played together, that sound good
  • and we've learned about Major, Minor, and Diminished chords.

Now, since a Key is a limited set of notes used in a song, not all chords fit in a given Key. Some will be Major, some will be Minor, and some will be Diminished.

The chords that fit in a particular Key are called Diatonic Chords.

Which chords fit into the Key of C Major?

To do this, make sure that all the notes in the chord are also in the Key. Hover over each choice to see the included notes.

C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
0
1
2
3
4
5
6
7
1.
C Major Chord
C Minor Chord
C Diminished Chord
2.
D Major Chord
D Minor Chord
D Diminished Chord
3.
E Major Chord
E Minor Chord
E Diminished Chord
4.
F Major Chord
F Minor Chord
F Diminished Chord
5.
G Major Chord
G Minor Chord
G Diminished Chord
6.
A Major Chord
A Minor Chord
A Diminished Chord
7.
B Major Chord
B Minor Chord
B Diminished Chord

How about E Major?

Again select the chords where all of its notes are in the Key. Hover over each choice to see the included notes.

C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
C#
D♭
D
D#
E♭
E
F
F#
G♭
G
G#
A♭
A
A#
B♭
B
C
0
1
2
3
4
5
6
7
1.
E Major Chord
E Minor Chord
E Diminished Chord
2.
F# Major Chord
F# Minor Chord
F# Diminished Chord
3.
G# Major Chord
G# Minor Chord
G# Diminished Chord
4.
A Major Chord
A Minor Chord
A Diminished Chord
5.
B Major Chord
B Minor Chord
B Diminished Chord
6.
C# Major Chord
C# Minor Chord
C# Diminished Chord
7.
D# Major Chord
D# Minor Chord
D# Diminished Chord

Seven Triads in Any Key

Look at the pattern of chords above. Notice how they are identical for both C Major and E Major?

Well, it turns out that every Major Key has 7 triads that follow the same pattern: Major, minor, minor, Major, Major, minor, Diminished.

You can use our Chord Finder to see the Diatonic Chords of any Key. This is very handy when switching a song from one Key to another.

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