Introduction to Chords

Fundamentals of Chords Introduction Chords are the foundation of harmonic music. They create the rich, layered sound we hear beneath melodies and give music its sense of direction, stability, and emotion. Understanding what chords are, how they're constructed, and how composers use them is essential to grasping how Western music works. What is a Chord? A chord is a group of three or more different pitches sounded together simultaneously. The key requirement is that you need at least three different pitch classes—individual notes—played at the same time. When just two notes sound together, that's called a dyad or interval, not yet a chord. The moment a third note joins, you've created a chord. Chords don't happen by accident in Western music. Instead, they're built systematically from the notes of a major or minor scale. This structured approach is what allows composers to create harmony that feels intentional and controlled, rather than random. The Role of Chords in Music Chords serve several critical functions in Western music: They create harmony. Chords are the vertical building blocks of music, providing the harmonic support beneath melodies. They establish stability or tension. Some chords feel "at rest" (stable), while others feel unresolved (tense), which composers use to guide listeners' emotional responses. They create movement. By moving from one chord to another in sequence—called a chord progression—composers create a sense of departure and arrival that drives a piece forward. Think of chords as the scaffolding of a piece of music: they hold everything together while the melody decorates the structure. Triads: The Three-Note Building Block What is a Triad? A triad is the most common type of chord. It consists of exactly three notes stacked in a specific way: a root (the bottom note that names the chord), a third (counted up three scale degrees from the root), and a fifth (counted up five scale degrees from the root). The names "third" and "fifth" come from counting scale degrees. If we're building a C triad, we start on C (the root), count up to E (the third), and count up to G (the fifth). All triads follow this three-note stacking pattern, but what varies is the quality—the specific intervals between the notes. Major Triads A major triad has a bright, open sound. It consists of: A major third ($4$ semitones above the root) A perfect fifth ($7$ semitones above the root) For example, a C major triad is C–E–G. If you count semitones: C to E is 4 semitones (a major third), and C to G is 7 semitones (a perfect fifth). This specific interval arrangement creates the characteristic major chord sound. Minor Triads A minor triad has a darker, more introspective sound. The only difference from a major triad is one note: the third is lowered by one semitone. A minor triad consists of: A minor third ($3$ semitones above the root) A perfect fifth ($7$ semitones above the root) For example, an A minor triad is A–C–E. Compare this to A major (A–C#–E): the C# has been lowered to C. This single semitone change dramatically affects the color and feeling of the chord. Diminished and Augmented Triads Beyond major and minor, two other triad types exist: Diminished triads lower the fifth by one semitone from what a minor triad has: A minor third ($3$ semitones above the root) A diminished fifth ($6$ semitones above the root) The diminished fifth is also called a tritone, and it creates a tense, unstable, almost eerie sound. A C diminished triad is C–E♭–G♭. Augmented triads raise the fifth by one semitone from what a major triad has: A major third ($4$ semitones above the root) An augmented fifth ($8$ semitones above the root) This also sounds tense and unstable, but in a different way—almost suspended or floating. A C augmented triad is C–E–G#. Diatonic Triads: Chords Built from a Major Scale What Are Diatonic Triads? When you build triads on each scale degree of a major key, you get a set of seven triads called diatonic triads. These seven chords "belong" to that key and sound natural together because they all use only the notes from that key's scale. If you're in the key of C major (C–D–E–F–G–A–B), you can build a triad starting from each note: Start on C: C–E–G (major) Start on D: D–F–A (minor) Start on E: E–G–B (minor) Start on F: F–A–C (major) Start on G: G–B–D (major) Start on A: A–C–E (minor) Start on B: B–D–F (diminished) Notice the pattern: some are major, some are minor, and one is diminished. This pattern is the same in every major key. Roman Numeral Notation Musicians use Roman numerals to label these triads. Capital numerals indicate major chords, lowercase indicates minor, and "°" indicates diminished: I – major ii – minor iii – minor IV – major V – major vi – minor vii° – diminished This notation is invaluable because it works for any major key. If you know that the progression is I–IV–V in a key, you can transpose it to any other key and it will have the same harmonic function and feel. A Fundamental Chord Progression One of the most important progressions in Western music is I–IV–V–I. This progression creates a journey: it leaves the home chord (I), moves away through IV and V, and then returns home to I. You'll hear this progression in countless folk songs, pop songs, and classical pieces. The reason it's so powerful is harmonic function. The I chord feels like "home." The V chord creates tension and points back toward I. The IV chord provides a departure point. Together, this progression captures the essential tension and release that makes music emotionally compelling. Chord Inversions: Reordering the Notes What is an Inversion? An inversion changes which note of the chord is the lowest sounding note (the bass note). When the root is the lowest note, the chord is in root position. When any other note of the chord is lowest, it's inverted. Why does this matter? Inversions don't change what chord it is—C–E–G and E–G–C are both C major chords—but they change how the chord sounds and how it connects smoothly to neighboring chords. Inversions are crucial for voice-leading, the technique of smoothly moving from one chord to the next. First Inversion In first inversion, the third of the chord becomes the lowest note. A C major chord in first inversion would be E–G–C. Musicians write this as a Roman numeral with a superscript 6: I⁶ (read as "one-six"). The "6" comes from interval analysis: in first inversion, the bass note and the root are a sixth apart. The chord sounds lighter and less stable than root position because the root is no longer at the bottom providing a foundation. Second Inversion In second inversion, the fifth of the chord becomes the lowest note. A C major chord in second inversion would be G–C–E. Musicians write this as I⁶₄ (read as "one-six-four"). Second inversion chords have a hollow, open quality and are typically used in specific harmonic contexts—most commonly the V⁶₄–V–I progression near the end of a piece, where the second inversion chord creates a sense of buildup before the final resolution. The Effect of Inversions The beauty of inversions is that they let composers achieve smooth voice-leading while maintaining harmonic function. Instead of jumping around awkwardly between root positions, inversions allow individual notes to move by step or small intervals, creating graceful, singable lines. Inversions also subtly change the color of a chord—its emotional quality. A chord in root position feels grounded; in first inversion, it feels lighter; in second inversion, it feels more open and spacious. These subtle differences are powerful tools for composers shaping how music feels. Seventh Chords: Four-Note Harmony What is a Seventh Chord? A seventh chord extends a triad by adding one more note: a pitch a seventh interval above the root. While triads contain three notes (root, third, fifth), seventh chords contain four. For example, a C major seventh chord is C–E–G–B. The B is the added seventh—it's a seventh above C. Adding this note creates richer, more complex harmony than a simple triad. Types and Function The most common seventh chord type is the major seventh (major triad + major seventh interval), but many others exist, including dominant sevenths, minor sevenths, and half-diminished sevenths. Each type has a different quality and harmonic function. The key thing to understand is that seventh chords are extensions of triads. They keep all the identity and function of the underlying triad but add an additional layer of color and tension. Seventh Chords in Modern Music Seventh chords are extremely common in jazz, blues, pop, and contemporary classical music. Where triads give you basic harmony, seventh chords let composers add sophistication and richness. A simple pop progression like I–IV–V becomes much more interesting when those chords become seventh chords: Imaj7–IVmaj7–V7. The addition of even one note dramatically expands the possibilities for expression and emotional nuance in music.