Learn how chords actually work
A visual, beginner-friendly guide to notes, intervals, scales, chords, and progressions — explained from the piano keyboard up.
Practice these ideas in the app1. Why Music Theory Helps
Music theory is a way to name the patterns you already hear. It does not tell you what you are allowed to play — it helps you understand why certain notes, chords, and progressions sound the way they do.
This guide starts from the piano keyboard and builds step by step: notes, intervals, scales, chords, inversions, and common progressions. You do not need to memorize everything at once. The goal is to make each idea visible and playable.
By the end, you should be able to:
- ✓Find and name notes on the piano
- ✓Understand basic staff notation
- ✓Build major and minor scales from a pattern
- ✓Build common chord types in any key
- ✓Recognize common chord progressions
- ✓Understand keys, modes, and the circle of fifths
2. The Musical Alphabet
On the piano, notes are named with seven letters: A, B, C, D, E, F, and G. After G, the pattern starts again at A, and those letters repeat across the keyboard.
The black keys sit between certain white keys. Each black key can usually be named two ways: as a sharp (♯) or as a flat (♭). C♯ and D♭ are the same piano key; they are enharmonic equivalents.
Find C first
Look for a group of two black keys. The white key immediately to the left is C. This is the easiest way to find your place anywhere on the keyboard.
What is an octave?
An octave is the distance from one note to the next note with the same name, like C to the next C. On the piano, that span contains 12 keys: 7 white keys and 5 black keys. Notes an octave apart sound closely related, just higher or lower.
The chromatic scale
If you play every key in order — white and black, with no skips — you are playing the chromatic scale. It has 12 notes, and each note is one half-step from the next.
3. Reading the Staff
You do not need to read sheet music to start learning chords, but basic staff notation helps you understand how piano music is written. Sheet music uses a staff: five lines and four spaces. A clef at the beginning tells you which notes those lines and spaces represent. Piano music usually uses treble clef for higher notes and bass clef for lower notes.
Treble Clef
Lines from bottom to top: E, G, B, D, F. Spaces from bottom to top: F, A, C, E.
Bass Clef
Lines from bottom to top: G, B, D, F, A. Spaces from bottom to top: A, C, E, G.
The Grand Staff
Piano music often uses treble and bass clef together. Middle C sits between them on a small ledger line, acting like a bridge between the hands.
Note Durations
Notes also show rhythm. A whole note usually lasts 4 beats, a half note 2 beats, a quarter note 1 beat, an eighth note ½ beat, and a sixteenth note ¼ beat.
Time Signatures
A time signature tells you how beats are grouped. In 4/4, the top number means 4 beats per measure, and the bottom number means the quarter note gets one beat. That is why 4/4 is often counted as 1-2-3-4.
4. Intervals
An interval is the distance between two notes. On the piano, the simplest way to measure that distance is by counting half-steps: one key to the very next key, black or white.
Intervals matter because they are inside everything else. Scales are patterns of intervals. Chords are notes stacked at specific intervals. Once intervals start to feel familiar, scales and chords become much easier to understand.
The two smallest distances
A half-step is the distance from one key to the very next key. A whole-step is two half-steps: you skip exactly one key in between. These two distances are the basic measuring units for scales.
Half-Step (1 semitone)
The smallest distance on the piano. Because the notes are so close together, a half-step often sounds tense or like it wants to move.
Whole-Step (2 semitones)
Two half-steps. A whole-step has more space between the notes, so it usually feels less tense than a half-step.
The 12 intervals
Each tile shows an interval measured from C: its name, size in half-steps, general sound, and piano keys. Click a tile to hear it. The exact notes can change, but the interval shape stays the same in every key.
Three intervals worth knowing early
These intervals come back again and again in chords, keys, and progressions. Learn to see them on the keyboard first; the names will become easier afterward.
Perfect 5th (7 semitones)
A very stable interval. It appears in most basic chords and strongly shapes the feeling of root movement in progressions.
Major 3rd / Minor 3rd (4 / 3 semitones)
The difference between these two is only one half-step, but it is what separates major and minor chords.
Tritone (6 semitones)
A tense interval that often wants to resolve. It is especially important inside dominant 7 chords.
5. The Major Scale
A scale is a selected set of notes organized around a home note, called the tonic. The major scale uses seven notes in a specific pattern of whole-steps and half-steps.
The pattern defines the scale. In C major, the pattern happens to use only white keys: C-D-E-F-G-A-B-C. In other keys, you use black keys when needed to keep the same pattern.
The pattern: W-W-H-W-W-W-H
Whole, whole, half, whole, whole, whole, half. From C, that gives C-D-E-F-G-A-B-C. From G, it gives G-A-B-C-D-E-F♯-G. Same pattern, different starting note.
Tonic and leading tone
Each note in a scale can be numbered from 1 to 7. Degree 1 is the tonic — the note that feels like home. Degree 7 is the leading tone in major keys because it sits one half-step below the tonic and naturally pulls upward.
6. Minor Scales
Minor scales are also seven-note patterns built from a tonic. Compared with the major scale, the 3rd is lowered, which gives minor scales their different color. The 6th and 7th can change depending on the type of minor scale.
Natural Minor
Pattern: W-H-W-W-H-W-W. From A, this uses only white keys: A-B-C-D-E-F-G-A. Natural minor has a lowered 3rd, 6th, and 7th, giving it a softer and darker sound than major.
Harmonic Minor
Harmonic minor is natural minor with the 7th raised. That raised 7th sits one half-step below the tonic, so it creates a stronger pull back home. This is why harmonic minor is often used when building the V chord in a minor key.
Melodic Minor
Melodic minor raises both the 6th and 7th on the way up. In classical music, those notes often return to natural minor on the way down; in jazz, the raised form is commonly used both ways. Raising the 6th smooths out the jump created by harmonic minor.
7. Modes
A mode is a scale you get by taking the notes of a major scale and treating a different note as home. The notes may be the same, but the center changes. For example, the white keys from C to C give C major; the same white keys from D to D give D Dorian. You do not need to memorize all seven modes at once — for now, just notice how changing the home note changes the color.
The seven modes
- Ionian — the major scale itself. Major 3rd, major 7th. Bright and resolved.
- Dorian — minor 3rd, major 6th, minor 7th. It sounds minor, but the raised 6th gives it a smoother, brighter color than natural minor. Common in jazz, funk, and modal grooves.
- Phrygian — minor 3rd, minor 2nd. The half-step above the tonic gives it a tense, Spanish, flamenco, or metal-like edge.
- Lydian — major 3rd, raised 4th. The raised 4th creates a floating, bright, slightly unreal sound often used in film music.
- Mixolydian — major 3rd, minor 7th. It sounds major, but less resolved than the major scale because it does not have a leading tone. Common in blues, rock, funk, and gospel.
- Aeolian — the natural minor scale. Minor 3rd, minor 6th, minor 7th. The standard natural minor sound.
- Locrian — minor 3rd, minor 2nd, diminished 5th. Because the 5th is lowered, the tonic feels unstable. It is used more often over half-diminished chords than as a home key.
Try the modes in the Practice Lab below ↓
8. Pentatonic & Blues Scales
A pentatonic scale uses five notes instead of seven. Because it leaves out the notes that most often create half-step clashes, it is very forgiving and easy to use over many chords.
Major Pentatonic
Degrees 1-2-3-5-6 of the major scale. It leaves out the 4th and 7th. Bright, open, and common in folk, country, gospel, and pop melodies.
Minor Pentatonic
Degrees 1-♭3-4-5-♭7. A core sound in blues, rock, funk, and many guitar and keyboard solos.
Blues Scale
Minor pentatonic plus the ♭5, often called the blue note. The ♭5 is usually treated as a passing note or expressive color, which gives blues lines their bite.
9. Key Signatures & the Circle of Fifths
A key is a scale that a piece of music treats as home. The key signature appears at the beginning of a staff and tells you which sharps or flats are normally used in that key.
The circle of fifths organizes major keys and their relative minors by perfect fifths. Moving clockwise adds sharps; moving counterclockwise adds flats. Neighboring keys share many notes, which is why they often sound natural next to each other.
Relative Major & Minor
Every major key has a relative minor that uses the same notes and the same key signature. The relative minor starts on degree 6 of the major scale. C major and A minor are relatives because they both use only the white keys.
Interactive Circle of Fifths
Click any segment to see the key signature, relative minor, and notes of the major scale.
10. Triads
A triad is a three-note chord: a root, a third, and a fifth. The root names the chord. The third usually tells you whether it is major or minor. The fifth helps the chord feel stable, unless it is raised or lowered.
How they're built
Triads are often explained as two stacked thirds. Major: major 3rd then minor 3rd. Minor: minor 3rd then major 3rd. Diminished: two minor 3rds. Augmented: two major 3rds.
MMajor Triad
Root + major 3rd + perfect 5th. Intervals from the root: 4 and 7 semitones. A stable chord with a major color.
mMinor Triad
Root + minor 3rd + perfect 5th. Intervals from the root: 3 and 7 semitones. Only one half-step changes from major, but the color changes a lot.
°Diminished Triad
Root + minor 3rd + diminished 5th. Intervals from the root: 3 and 6 semitones. The lowered 5th creates tension and usually wants to move somewhere.
+Augmented Triad
Root + major 3rd + augmented 5th. Intervals from the root: 4 and 8 semitones. Because the 5th is raised, the chord sounds bright but unsettled.
Suspended chords (sus2 / sus4)
A suspended chord replaces the third with a 2nd or a 4th. Because there is no third, the chord is neither clearly major nor clearly minor. It sounds open, and often resolves when the missing third appears.
Sus2
Root + major 2nd + perfect 5th. Open and airy.
Sus4
Root + perfect 4th + perfect 5th. The 4th often resolves down to the 3rd, which is why sus4 chords can feel like they are waiting to settle.
11. Seventh Chords
A seventh chord is a triad with one extra note: the seventh above the root. That added note gives the chord more color and tension. Seventh chords are especially common in jazz, gospel, R&B, soul, blues, bossa nova, and modern pop harmony.
Common seventh chords
Major 7 (maj7)
Major triad + major 7th. The 7th sits one half-step below the octave, giving the chord a smooth, lush sound.
Minor 7 (m7)
Minor triad + minor 7th. The 7th sits a whole-step below the octave, giving the chord a softer and more open minor sound.
Dominant 7 (7)
Major triad + minor 7th. This chord has a strong pull toward resolution, especially when it is built on the 5th degree of a key.
Half-Diminished (m7♭5)
Diminished triad + minor 7th. Also called half-diminished. Common in minor-key progressions, especially before a dominant chord.
Diminished 7 (°7)
Diminished triad + diminished 7th. Built from stacked minor 3rds. Very tense, and often used to connect chords or create dramatic movement.
Minor-Major 7 (mMaj7)
Minor triad + major 7th. The minor 3rd and major 7th create a tense, dramatic color often heard in spy-film-style harmony.
12. Inversions & Extensions
A chord is defined by the notes it contains, not only by the note at the bottom. C major is C-E-G, but it can also be played E-G-C or G-C-E. These rearrangements are called inversions. They help chords connect more smoothly on the keyboard.
Root Position
Root note on the bottom (C-E-G).
1st Inversion
Third on the bottom (E-G-C). The root has been moved up an octave.
2nd Inversion
Fifth on the bottom (G-C-E). Both the root and the third have been moved up an octave.
💡 When moving from one chord to the next, choose notes that move as little as possible. Keep shared notes in place, and move the others to the nearest chord tone. This is voice leading.
Extensions: 9, 11, and 13
Extensions are notes added above a seventh chord. A 9 is like a 2nd moved up an octave, an 11 is like a 4th moved up an octave, and a 13 is like a 6th moved up an octave. These notes are usually placed higher in the chord to add color.
On piano, you usually do not need to play every note in a big chord. The 3rd and 7th often define the chord quality, while extensions add color. The root may be played by the left hand, a bass player, or left out when the harmony is already clear.
13. Diatonic Chords & Progressions
If you build a triad on each note of a major scale, using only notes from that scale, you get the seven diatonic chords of the key. In C major, they are C, Dm, Em, F, G, Am, and B°.
Musicians often label these chords with Roman numerals. Uppercase means major, lowercase means minor, and the small degree sign means diminished. Roman numerals are useful because the same progression can be moved to any key.
The seven diatonic chords in C major
One triad built on each note of the C major scale
Tonic, Subdominant, Dominant
Diatonic chords can be grouped by function. Tonic chords feel close to home. Predominant or subdominant chords move away from home. Dominant chords create the strongest pull back home. Progressions often work by moving through these areas of tension and release.
Common Progressions
Once you know Roman numerals, you can recognize the same chord patterns in many different keys. A song in C and a song in G may use different chord names, but the same Roman numeral pattern.
I-V-vi-IV — The Pop Progression
One of the most common four-chord loops in modern pop. In C: C-G-Am-F. The vi chord gives the progression a softer emotional turn before it returns toward IV and I.
I-vi-IV-V — The 50s / Doo-Wop
A classic doo-wop-style loop. In C: C-Am-F-G. It starts at home, moves to the relative minor, then uses IV and V to lead naturally back to I.
ii-V-I — The Jazz Cadence
In C: Dm-G-C, or with sevenths: Dm7-G7-Cmaj7. The ii chord prepares the V, and the V resolves to I. This is one of the most important movements in jazz harmony.
12-Bar Blues
A 12-bar form built mainly from I, IV, and V. In blues, these chords are often played as dominant 7 chords, which keeps the harmony expressive and slightly unresolved.
12 bars · 3 chords · one of the roots of blues, rock, R&B, and gospel
14. Cadences, Voice Leading & What to Learn Next
A cadence is a chord movement that ends a phrase, like punctuation in a sentence. Some cadences sound finished; others sound like the music is pausing and will continue.
Authentic (V → I)
V → I. This is the clearest resolution in tonal music. It sounds finished because the dominant chord strongly pulls back to the tonic.
Plagal (IV → I)
IV → I. A gentler resolution than V → I. This is often called the “amen” cadence because it appears at the end of many hymns.
Half (... → V)
A phrase that ends on V. It feels unfinished, like a comma, because the dominant chord is still waiting to resolve.
Deceptive (V → vi)
V → vi. The dominant chord seems ready to resolve to I, but lands on vi instead. Because vi shares notes with I, the move is smooth but surprising.
Voice Leading
Voice leading means connecting chords with smooth movement. Keep any shared notes, and move the other notes to the nearest available notes in the next chord. On piano, this often feels easier under the fingers and sounds more connected.
Where to Go From Here
Once you understand notes, intervals, scales, keys, chords, inversions, seventh chords, progressions, and cadences, you have the foundation for a lot of real music. Useful next topics include:
- 1Secondary dominants — using the V chord of another chord to create a stronger pull into it.
- 2Modal interchange — borrowing chords from the parallel minor or major key for extra color.
- 3Tritone substitution — replacing a dominant 7 chord with another dominant 7 chord a tritone away, a common jazz sound.
- 4Reharmonization — keeping a melody but changing the chords underneath it.
- 5Counterpoint — writing two or more melodic lines that work together.
You do not need all of that right away. The most important next step is to connect the theory with your hands: play the chords, hear the differences, and notice the same patterns in real songs.
Practice Lab
Pick a root note, then build a scale or chord. Use the lab to check what you just learned and to find sounds you like.
Interactive Scale Explorer
Pick a root and scale type to see the pattern on the keyboard.
C Major (Ionian)
Interactive Chord Explorer
Pick a root and chord type, then see and hear the notes on the keyboard.
C Major
Now put it under your fingers
Reading about theory helps, but chords become useful when your hands can find them quickly. Piano Chords Teacher listens to your MIDI keyboard and turns chord practice into a real-time game.
Try the practice app