Chords: notes that play together

What is a chord?

When you play notes one after another, you get a melody: the tune you sing along to. When you play three or more notes at the same time, you get a chord: the sound that goes underneath the tune.

A strummed guitar and a pianist's left hand both play chords. Press the buttons to hear the same three notes played one by one, and then together.

Building a chord: a tower of three notes

Most chords are built like a tower. Choose a starting note, called the root: it gives the chord its name. Skip one note of the scale and take the next. Skip another and take the next. Now you have three notes.

On the white keys from C: start on C, skip D, take E, skip F, take G. The tower is C E G, and it is called a C major chord. The other two notes are a third and a fifth above the root (see the lesson on intervals). A chord of three notes built this way is called a triad.

Try other starting notes in the builder below. The tower is built the same way, but each root gives a different sound.

Major and minor: bright and sad

A triad has two blocks: a lower block between the root and the middle note, and an upper block between the middle note and the top note. In a major chord the lower block is bigger (4 half steps) and the upper block is smaller (3 half steps). In a minor chord it is the other way round: 3 and then 4.

That one half step changes the mood. Major chords usually sound bright and open. Minor chords usually sound softer and more serious, sometimes sad. Listen to C major and C minor one after the other: only the middle note moves down by one half step.

Neither one is better. Songs often mix them, like sunshine and clouds in the same day.

Try it: press the two buttons one after the other, three times. Which one sounds like a smile, and which like a cloud?

Two more colours: diminished and augmented

Two more towers are built from two blocks of the same size. A diminished chord has two small blocks (3 + 3 half steps). It sounds tense, as if something is about to happen. An augmented chord has two big blocks (4 + 4 half steps). It sounds dreamy and unsettled, like floating.

You will meet these less often than major and minor, but now you can hear all four triads side by side. The names are written the way musicians write them: C (major), Cm, Cdim and Caug.

1. Major chordC

   half steps: 4 + 3Notes: C E G

   Bright and open.

   Play
2. Minor chordCm

   half steps: 3 + 4Notes: C E♭ G

   Soft and serious, sometimes sad.

   Play
3. Diminished chordCdim

   half steps: 3 + 3Notes: C E♭ G♭

   Tense, as if something is about to happen.

   Play
4. Augmented chordCaug

   half steps: 4 + 4Notes: C E G♯

   Dreamy and unsettled, like floating.

   Play

A fourth note: seventh chords

Add one more third on top of a triad and you get a seventh chord, with four notes. The new top note is a seventh above the root. Three seventh chords are very common: the major seventh (Cmaj7), the plain seventh (C7) and the minor seventh (Cm7).

You can think of a seventh chord as a triad with a little extra colour on top.

1. Major seventh chordCmaj7

   half steps: 4 + 3 + 4Notes: C E G B

   Smooth and dreamy.

   Play
2. Seventh chordC7

   half steps: 4 + 3 + 3Notes: C E G B♭

   Bluesy and restless, as if it wants to go somewhere.

   Play
3. Minor seventh chordCm7

   half steps: 3 + 4 + 3Notes: C E♭ G B♭

   Mellow and cool.

   Play

Chords that belong together

Each key has its own family of chords. Take a major scale and build a triad on every note, using only the notes of that scale. You get seven chords. Musicians number them with Roman numerals: capital letters for major chords and small letters for minor and diminished chords.

In a major key the pattern is always the same: I is major, ii is minor, iii is minor, IV is major, V is major, vi is minor and vii° is diminished. In the key of C, the family is C, Dm, Em, F, G, Am and B°.

Pick a key and press the buttons to hear its chord family. The chords I, IV and V are all major, and songs use them a lot.

Four chords, many songs

A chord progression is a list of chords played in order, usually repeating. One very common progression is I – V – vi – IV. In the key of C that is C, G, Am and F.

Many pop songs use these same four chords, in this order or in another order, with different melodies on top. Press a button to hear a progression, then pick another key: the pattern stays the same and only the starting note changes.

Little quiz: major or minor?

Listen to the chord. Does it sound like a bright major chord or a softer minor chord?