What Are Chords?
Learn how combinations of notes create mood and movement
A chord = multiple notes played together. The atmosphere of a song—bright, calm, or tense—comes from its chords.
1) Why chords matter
If melody is the lead, chords are the background. Change the chord, and the same melody takes on a new mood. Knowing chords lets you recreate a feeling on purpose.
Example: in “Let It Be,” the flow C–G–Am–F balances home and motion. With theory, you can explain why it feels right.
2) Core idea — build by stacking thirds
Chords are built by stacking 3rds. The basic unit is Root (1) + 3rd (3) + 5th (5) — a triad.
- Root→3rd: major 3rd (4 semitones) or minor 3rd (3 semitones)
- Root→5th: perfect 5th (7 semitones) (with some exceptions)
Thinking in intervals lets you derive chords in any key without rote memorization.
3) Triad types
| Name | Formula (degrees) | Notes in C | Character |
|---|---|---|---|
| Major | 1–3–5 | C–E–G | Bright, stable |
| Minor | 1–♭3–5 | C–E♭–G | Moody, introspective |
| Diminished | 1–♭3–♭5 | C–E♭–G♭ | Tense, unstable |
| Augmented | 1–3–#5 | C–E–G# | Floating, forward motion |
Master major/minor first. Hear dim/aug as colors you can add.
4) Seventh chords — M7, 7, m7
Add one more 3rd on top and you get a seventh chord (four-note chord). Start with these three:
| Name | Formula | Notes in C | Character / Usage |
|---|---|---|---|
| Major seventh (M7) | 1–3–5–7 | C–E–G–B | Smooth, sophisticated; ballads/city pop/jazz |
| Dominant seventh (7) | 1–3–5–♭7 | C–E–G–B♭ | Urgent, bluesy; wants to resolve to the next chord |
| Minor seventh (m7) | 1–♭3–5–♭7 | C–E♭–G–B♭ | Settled, soulful; common in II–V–I |
Quick ear guide: M7 = melts, 7 = pushes forward, m7 = smoky & calm.
5) Roles of the 3rd and 7th
- 3rd … sets the major/minor color.
- 7th … sets the direction (rest vs. go). ♭7 in a dominant 7 strongly pushes forward.
When the melody’s use of the 3rd (up/down) fits with the chord’s 3rd/7th placement, the song’s expressiveness stands out.
6) What is a chord progression?
A single chord sets a mood; a sequence makes music move. Chord progressions are the blueprint for a song’s flow and story.
Examples:
- C–Am–F–G — classic, sentimental.
- Dm–G–C — jazz staple II–V–I; adding 7ths makes the pull obvious.
- E–A–B–E — rock strength (works as power chords, too).
We’ll unpack this systematically in “What Is Diatonic?”
7) Try it in the app
With OtoTheory you listen while you learn:
- Tap to compare major/minor and M7/7/m7.
- Reorder to feel II–V–I direction.
- Add 7ths/9ths as color.
- Save favorites to My Progressions.
8) Summary
- Build chords by stacking thirds; start with 1–3–5.
- Triads: major/minor (plus dim/aug as colors).
- Seventh chords: M7 / 7 / m7 are the core; 3rd = color, 7th = direction.
- Progressions tell stories; II–V–I reveals pull.
- Use the app to connect ear and theory.