What Is a Chord?
A chord is three or more notes played simultaneously. Chords are the harmonic backbone of music — they create the mood, tension, and resolution that give a song its emotional character. Understanding chords is essential whether you want to play classical pieces, accompany songs, improvise, or write your own music.
The Building Block: The Triad
The most fundamental chord type is the triad — a three-note chord built by stacking two intervals of a third. Every triad has a root (the bottom note that names the chord), a third, and a fifth.
The Four Types of Triads
| Chord Type | Formula | Sound | Example (root C) |
|---|---|---|---|
| Major | Root + 4 semitones + 3 semitones | Bright, happy | C – E – G |
| Minor | Root + 3 semitones + 4 semitones | Dark, melancholic | C – E♭ – G |
| Diminished | Root + 3 semitones + 3 semitones | Tense, unstable | C – E♭ – G♭ |
| Augmented | Root + 4 semitones + 4 semitones | Mysterious, unresolved | C – E – G♯ |
How to Build Any Major Chord
To build a major chord on any root note:
- Start on the root note (e.g., G)
- Count up 4 semitones (half steps) to find the major third (e.g., B)
- Count up 3 more semitones to find the perfect fifth (e.g., D)
Result: G major = G – B – D. Apply this formula to any of the 12 notes and you'll have all 12 major chords.
Chord Inversions: More Than One Way to Play a Chord
A chord doesn't always have to be played with the root on the bottom. Inversions rearrange the notes so a different note is in the bass:
- Root position: Root on the bottom (C – E – G)
- First inversion: Third on the bottom (E – G – C)
- Second inversion: Fifth on the bottom (G – C – E)
Inversions are incredibly useful for keeping smooth voice leading — moving between chords without jumping your hands all over the keyboard. They also create different bass sounds and colours even when the chord name is the same.
Common Chord Progressions to Practice
Once you know your basic triads, these progressions will unlock hundreds of songs:
- I – IV – V – I (e.g., C – F – G – C): The foundation of blues, folk, and rock
- I – V – vi – IV (e.g., C – G – Am – F): One of the most common pop progressions in the world
- ii – V – I (e.g., Dm – G – C): The cornerstone of jazz harmony
- I – vi – IV – V (e.g., C – Am – F – G): Classic 1950s doo-wop, used in countless pop ballads
Beyond Triads: 7th Chords
Adding one more note — a seventh — to a triad creates a richer, more complex sound called a seventh chord. The most important ones to know:
- Major 7th (Cmaj7): C – E – G – B — warm, lush, jazz and pop
- Dominant 7th (C7): C – E – G – B♭ — bluesy, creates strong pull to resolve
- Minor 7th (Cm7): C – E♭ – G – B♭ — smooth, soulful, ubiquitous in jazz and R&B
Getting Started with Chords in Practice
- Learn the major triads for all 12 notes — practice until each one is instant
- Then learn the minor triads for all 12 notes
- Practice the I–V–vi–IV progression in multiple keys
- Introduce inversions to smooth out chord transitions
- Gradually add 7th chords to your palette
Chords Unlock Music
Understanding chords transforms the piano from a melody instrument into a full harmonic world. With even a handful of chords, you can accompany songs, experiment with your own progressions, and start to understand the underlying logic in the music you love. Start with triads, practice them daily, and the rest will follow naturally.