Music theory, from the first note to the last symbol.

Music theory is the grammar of music: the names for what you hear, and the code for writing it down. You don’t need it to enjoy music, but it makes learning an instrument much faster, because a page of notes stops being a puzzle and becomes instructions. We start from nothing and build up, and every term is in the reference at the end if you only need to look one up.

Part one · Learn

1. Notes, pitch and the keyboard

Every musical sound has a pitch: how high or low it is. Western music names its pitches with just seven letters, A B C D E F G, and then starts again. The next A after G sounds like a higher copy of the first: it vibrates exactly twice as fast. That distance, from one note to the next note with the same name, is an octave.

The piano keyboard makes this easy to see. The black keys come in groups of two and three, and the pattern repeats every octave. C is always the white key just left of a group of two black keys. Find it, and you can name every other key by walking up the alphabet.

White keys, C to C Every key, C to C Three Cs, an octave apart

Count every key, black and white, from one C to the next and there are twelve. The step from any key to the very next one is a semitone (Americans say half step). Two semitones make a tone (a whole step). Most of music theory is counting those two steps.

Notice that E to F and B to C have no black key between them. Those pairs are already a semitone apart. Every other pair of white neighbours is a tone apart, with a black key in the middle.

A sharp (♯) raises a note by a semitone, and a flat (♭) lowers it by one. So the black key between C and D is both C♯ and D♭. Two names for one sound are called enharmonic. Which name you use depends on the key, as you’ll see in lesson 7.

2. The staff and clefs

Music is written on a staff (the British also say stave): five lines and the four spaces between them. Notes sit on a line or in a space. Higher on the staff means higher in pitch, and each step up, line to space to line, is the next letter of the alphabet.

The staff on its own doesn’t say which note is which. That’s the job of the clef at the start of every line.

The treble clef

The treble clef grew out of a fancy letter G, and it curls round the second line up to say this line is G, the G above middle C. It’s used for higher music: the right hand on the piano, the violin, flute, recorder, trumpet and most singers.

Hear the lines Hear the spaces

The bass clef

The bass clef began as a letter F. Its two dots sit either side of the fourth line, marking it as the F below middle C. It’s for lower music: the piano’s left hand, cello, bassoon, trombone, tuba and bass guitar.

Hear the lines Hear the spaces

Ledger lines, middle C and the grand staff

Notes too high or low for the staff get short extra lines of their own, ledger lines. Middle C sits on one ledger line below the treble staff, or one above the bass staff: the same note either way.

Piano music uses both clefs at once, a treble staff over a bass staff joined by a brace. That’s the grand staff. Middle C sits in the gap between them, which is why it’s the landmark every beginner learns first.

Hear it

The C clefs

A third kind of clef, the C clef, can sit on any line and marks that line as middle C. On the middle line it’s the alto clef, the viola’s clef. On the fourth line it’s the tenor clef, which cellists, bassoonists and trombonists use for high passages so they don’t need a forest of ledger lines.

3. Note lengths and rests

Where a note sits gives its pitch. Its shape gives its length, counted in beats. Each note is half the length of the one before it. Australia, Britain and New Zealand use the old names; Americans name them by fractions of a bar of 4/4. Both are right.

Hear the notes halve

The parts of a note are the head (the oval), the stem and, on quavers and shorter, a flag. Stems go up on the right for notes below the middle line, and down on the left for notes on or above it. When quavers come in groups, a beam replaces the flags and shows where each beat starts.

Every note has a rest of the same length: a measured silence. Watch the semibreve and minim rests. The semibreve rest hangs from the fourth line; the minim rest sits on the middle line. (“Hangs is heavier”: the longer rest hangs.) A semibreve rest also means “rest for the whole bar”, whatever the time signature.

The full list, with the longest and shortest, is in the note values chart.

Dots, ties and triplets

A dot after a note adds half its value again. A minim is 2 beats, so a dotted minim is 2 + 1 = 3. A dotted crotchet is 1 + ½ = 1½, and usually comes with a quaver to finish the beat.

Hear it

A tie is a curve joining two notes of the same pitch. Play the first and keep holding it through the second. It’s how a note can last across a bar line. A slur looks similar but joins different notes: it means play them smoothly, with no gap.

Hear it

A triplet squeezes three notes into the time of two, marked with a 3. Other tuplets work the same way: a 5 over five semiquavers means fit them into the time of four.

Hear it

4. Beats, bars and time signatures

Under most music is a steady pulse, the beat you tap your foot to. Beats fall into groups with a strong one first, and each group is written as a bar (Americans say measure), divided off by bar lines. A double bar line ends a section; a thin-and-thick one ends the piece.

The time signature, two numbers after the clef, says how the beats are grouped. The top number is how many beats are in each bar. The bottom number is which note gets one beat: 4 means a crotchet (a quarter of a semibreve), 2 a minim, 8 a quaver.

2/4 3/4 4/4

When the beat divides naturally into two (one-and, two-and), as in 2/4, 3/4 and 4/4, the time is simple. When each beat divides into three, the time is compound. 6/8 looks like six beats but is felt as two, each a dotted crotchet split into three quavers: ONE-and-a TWO-and-a. Jigs, nursery rhymes and lullabies love it. 9/8 is three of those beats and 12/8 four.

Hear 6/8

Two beats in a bar is duple time, three is triple and four is quadruple. A C with a line through it is cut time or alla breve, 2/2: two minim beats, so it moves along briskly. And some music uses irregular times such as 5/4 or 7/8, felt as uneven groups like 3 + 2.

Starting before the bar: the anacrusis

Many tunes start on a weak beat, before the first strong one. Those lead-in notes are the anacrusis (or pickup, or upbeat), and the last bar is usually short by the same amount, so the two add up to a full bar. Amazing Grace starts this way: “A-” comes before the bar line, “-ma-” lands on the first strong beat.

Hear it

Counting rhythms aloud

Musicians count beats as numbers and the half-beats in between as “and”: 1 & 2 & 3 & 4 &. Semiquavers get “e” and “a”: 1 e & a 2 e & a. In compound time, each beat is counted 1 & a 2 & a. Say it out loud while you clap the rhythm and the hardest-looking bar comes apart.

Syncopation is when the accent lands somewhere unexpected, off the beat or on a weak beat, so the rhythm pushes against the pulse. It’s the life of ragtime, jazz, funk and most pop.

Hear it

5. Sharps, flats and naturals

A sharp, flat or natural written in front of a note is an accidental. The rules for them are short and catch everyone out at least once:

• Sharp (♯) raises the note a semitone; flat (♭) lowers it a semitone.
• Natural (♮) cancels a sharp or flat, back to the plain white key.
• An accidental lasts until the end of the bar, for that note in that octave. The bar line cancels it.
• A double sharp raises a note two semitones (F double sharp sounds as G), and a double flat lowers it two.

Hear it

Some music prints a courtesy accidental, sometimes in brackets, in the next bar to remind you an accidental has worn off. It changes nothing.

6. Scales

A scale is a set of notes in order, step by step, from a starting note up to its octave. The starting note is the tonic or home note. What gives a scale its character is the pattern of tones (T) and semitones (S) between its steps.

The major scale

Play the white keys from C to C and you have the major scale: T T S T T T S. The two semitones fall between the 3rd and 4th notes (E–F) and the 7th and 8th (B–C). That pattern is what “major” means. Start it on any other note and you need black keys to keep the pattern, which is where keys come from.

C major G major F major

Each step of the scale has a name as well as a number. You’ll meet these names in harmony:

Minor scales

Play the white keys from A to A instead and the semitones land in different places: T S T T S T T. That’s the natural minor scale, and it sounds darker or sadder. The key difference is the 3rd note: three semitones above the tonic in minor, four in major.

Natural minor has a weakness: its 7th note is a whole tone below the tonic, so it doesn’t pull home strongly. Composers fixed that two ways. The harmonic minor raises the 7th a semitone (G♯ in A minor), which leaves an exotic-sounding gap of three semitones between the 6th and 7th. The melodic minor smooths that gap by raising the 6th as well on the way up, then lowers both again on the way down.

Natural Harmonic Melodic

Pentatonic, blues and the rest

Plenty of music uses other scales. The pentatonic has five notes and no semitones, so nothing in it clashes: play only the black keys and you’re playing one. It underlies folk songs from Scotland to China and most rock guitar solos. The blues scale adds one “blue note” to the minor pentatonic. The chromatic scale is every semitone in order, and the whole-tone scale is all tones, six notes that never quite settle.

Pentatonic Blues Whole tone

The scales chart in the reference lists them all with their step patterns.

Modes

Start the white-key scale on a note other than C or A and you get one of the modes, named after the old church modes, and which folk, jazz and film music never gave up. Each has its own flavour, because the semitones land in different places relative to the home note.

7. Keys, key signatures and the circle of fifths

A piece built on the G major scale is in the key of G major: G is home, and the tune and the chords tend to end there. Rather than write a sharp in front of every F, the music sets out the sharps or flats once, after the clef on every line. That’s the key signature, and it applies to every note of that name, in every octave, all the way through.

Sharps and flats always appear in the same order, so a key signature can only ever be the first one, two, three and so on of them:

Two tricks name the key from its signature:

• Sharps: the last sharp is the leading note, so the key is a semitone above it. Last sharp C♯? The key is D major.
• Flats: the second-last flat is the key. B♭, E♭, A♭? E♭ major. (One flat is F major: learn that one.)

Every key signature serves two keys: a major and its relative minor, which starts three semitones lower. C major and A minor share no sharps or flats; G major and E minor share one sharp. To tell which you’re in, look at the last note and the last chord, and look for the minor key’s raised 7th (D♯ in E minor) as an accidental.

The circle of fifths

Go up a fifth from C and you reach G, with one sharp. Up a fifth again, D, with two. Keep going and you add one sharp each time, all the way round until the sharps turn into flats and you arrive back at C. Drawn as a clock, that’s the circle of fifths, the most useful single picture in music theory. Keys next to each other share all but one note, so music usually moves to a neighbour when it changes key.

8. Intervals

An interval is the distance between two notes. It has a number and a quality.

The number comes from counting letter names, counting both ends. C to E is a third (C, D, E: three letters). C to G is a fifth. C to the next C is an octave, the eighth.

The quality pins down the exact size, because a third can be three or four semitones. Unisons, fourths, fifths and octaves are perfect. Seconds, thirds, sixths and sevenths come in two sizes, major (larger) and minor (a semitone smaller). Stretch any interval one semitone wider than major or perfect and it’s augmented; squeeze it one narrower than minor or perfect and it’s diminished.

The table puts every interval inside an octave in order, with a well-known tune that starts with it. Singers learn intervals this way, and it works: once you can hear the jump between the two “twinkles” of Twinkle, Twinkle, you can hear a perfect fifth anywhere.

Turn an interval upside down, putting the lower note on top, and you get its inversion. The numbers always add to nine (a third becomes a sixth) and the quality flips: major becomes minor, augmented becomes diminished, perfect stays perfect.

Some intervals sound restful, consonant: octaves, fifths, fourths, thirds and sixths. Others sound tense, dissonant, and seem to want to move on: seconds, sevenths and the tritone. Most music is a play between the two.

9. Chords

A chord is three or more notes sounding together. The basic chord is the triad: three notes stacked in thirds, the root, the third and the fifth. On the piano, play a note, skip a white key, play the next, skip, play the next.

The two thirds in the stack can be major or minor, which gives four kinds of triad:

• Major: a major third, then a minor third. C E G. Bright.
• Minor: a minor third, then a major third. C E♭ G. Darker.
• Diminished: two minor thirds. C E♭ G♭. Tense.
• Augmented: two major thirds. C E G♯. Unsettled, dreamy.

Hear the four triads

The chords of a key

Build a triad on each note of a major scale, using only notes from the scale, and you get the seven chords that belong to that key. Musicians name them with Roman numerals, capitals for major and small letters for minor, so the pattern works in any key:

Hear them

The three major chords, I, IV and V (C, F and G in C major), are the primary chords. They contain every note of the scale between them, and they will harmonise thousands of simple songs on their own; every First piece in our kids’ sheet music uses only those three. In a minor key the natural minor scale gives i, ii°, III, iv, v, VI and VII; in practice v is usually made major (V) by raising the 7th, which also turns VII into vii°.

Inversions

The notes of a chord don’t have to sit root-at-the-bottom. With the root at the bottom the chord is in root position. With the third at the bottom it’s in first inversion; with the fifth at the bottom, second inversion. It’s the same chord, with a different bass note. Inversions let the hand move less and the bass line move smoothly, which is why the left-hand chords in beginner piano books are usually inverted.

Hear the inversions

Seventh chords and chord symbols

Stack one more third on a triad and you get a seventh chord, named after the new note’s distance from the root. The most important is the dominant seventh, chord V with a minor seventh on top (G B D F in C major). It has a tritone inside it, and it pulls so hard towards the tonic that it ends half the music ever written.

Hear them

Songbooks and lead sheets print chords as chord symbols above the staff. A letter alone is a major chord (C); m is minor (Cm); 7 is a dominant seventh (C7); maj7 a major seventh; dim or ° diminished; aug or + augmented; sus4 replaces the third with a fourth. A slash names the bass note: C/E is C major with E at the bottom, the first inversion. The chord formulas chart has the full set, and our piano chords page shows the common ones on the keyboard with fingering.

10. Harmony: progressions and cadences

Harmony is how chords follow one another. Some moves feel like travelling away from home, others like coming back, and a whole song is a journey of those moves. A string of chords is a chord progression, and a handful of them turn up everywhere:

I–IV–V–I I–V–vi–IV, the pop progression ii–V–I, the jazz one

The twelve-bar blues is a whole progression in one: four bars of I, two of IV, two of I, then V, IV, I and I (or V to go round again). In C: C C C C, F F C C, G F C G. Rock ’n’ roll grew out of it.

Hear a twelve-bar blues

Cadences: musical punctuation

The two chords at the end of a phrase make a cadence, and they work like punctuation:

• Perfect cadence, V to I: a full stop. The strongest way to end. (US: authentic.) Hear it
• Plagal cadence, IV to I: the “Amen” at the end of a hymn. A softer full stop. Hear it
• Imperfect cadence, anything to V: a comma, or a question. It sounds unfinished. (US: half cadence.) Hear it
• Interrupted cadence, V to vi: you expect home and get a surprise. (US: deceptive.) Hear it

Moving to a new key partway through a piece is modulation. Usually it’s to a close neighbour on the circle of fifths, most often the dominant (up a fifth) or the relative minor or major.

11. Melody, phrases and form

A melody is a line of notes heard as one shape, the part you’d sing. Melodies are built from small ideas, motifs, grouped into phrases that work like sentences, often four bars long and ending at a cadence. Two phrases often pair up as a question and an answer. Twinkle, Twinkle shows it: the first half rises and stops on G, open-ended; the second comes back down to C and closes.

Hear it

A phrase repeated straight away at a higher or lower pitch is a sequence. A short pattern repeated over and over underneath is an ostinato.

Zoom out and whole pieces have shapes too, called form, labelled with letters for each section:

• Strophic: the same music for every verse. Most hymns and folk songs.
• Binary (AB): two halves, each usually repeated. Many Baroque dances.
• Ternary (ABA): a section, a contrast, then the first again. A minuet with its trio.
• Rondo (ABACA): a main theme that keeps coming back between new episodes.
• Theme and variations: a tune, then a string of altered versions of it.
• Verse and chorus: verses with changing words around a chorus that repeats. Most pop songs, often with a contrasting bridge.
• 32-bar song form (AABA): two statements, a contrasting middle eight, the statement again. The jazz standards.
• Sonata form: an exposition that sets out two themes in two keys, a development that works them over, and a recapitulation that brings both back in the home key. The first movement of most Classical symphonies and sonatas.

12. Dynamics and articulation

Dynamics say how loud to play, with Italian words shortened to letters. p is piano, soft; f is forte, loud; m is mezzo, moderately. Double or triple the letter for more:

ppp · pp · p · mp · mf · f · ff · fff
softest ← → loudest

Changes are marked with hairpins: lines opening out for a crescendo (getting louder), closing in for a diminuendo or decrescendo (getting softer). sfz, sforzando, is a sudden accent on one note. Dynamics are relative: forte on a recorder and forte for an orchestra are very different volumes.

Hear it

Articulation is how each note starts, how long it’s really held and how it joins the next:

• Legato, shown by a slur: smoothly joined.
• Staccato, a dot over or under the note: short and detached. A wedge, staccatissimo, is shorter still.
• Accent (>): give the note extra weight. Marcato (^) is a stronger accent.
• Tenuto, a short line: hold the note for its full length, with a slight lean.
• Fermata, a dot under an arch: pause on the note, holding it longer than written.

Hear it

Ornaments, the small decorations such as trills, mordents and turns, are drawn and explained in the ornaments section of the reference.

13. Tempo

Tempo is the speed of the beat, measured in beats per minute (BPM). A metronome mark such as “crotchet = 120” at the top of the music means 120 crotchet beats a minute, two a second. A metronome ticks at whatever speed you set, and practising slowly with one is the surest way to play evenly.

Before metronomes, composers described the speed in words, and they still do. The words are mostly Italian and describe a mood as much as a speed: allegro means cheerful as well as fast. From slow to fast, the common ones are largo, adagio, andante (a walking pace), moderato, allegro and presto. The tempo chart gives the rest, with rough speeds.

Adagio, 70 Andante, 92 Allegro, 140 Presto, 184

Changes of speed: accelerando (accel.) gets gradually faster; ritardando (rit.) and rallentando (rall.) get gradually slower; ritenuto is slower at once. A tempo or tempo primo means back to the earlier speed. Rubato, “robbed time”, is the gentle stretching and catching up that makes a performance breathe.

14. Repeats and the road map of a score

Music saves paper by sending you back to play passages again. Read the signs before you start, so you know the route.

Repeat signs are double bar lines with two dots. Play what’s between them twice; if there’s no opening sign, go back to the start. First and second time bars (also called volta brackets or 1st and 2nd endings) give the passage a different ending each time: play the bar under bracket 1, go back, then skip bracket 1 and play bracket 2.

Hear the route

Longer jumps use Italian words and two signs, the segno (an S with a slash and two dots) and the coda sign (a circle crossed by two lines):

• D.C. (da capo, from the head): go back to the beginning.
• D.S. (dal segno, from the sign): go back to the segno.
• al Fine: then play until the word Fine (the end) and stop.
• al Coda: then play until To Coda, and jump to the coda sign for the ending.

So D.S. al Coda means: back to the segno, play to To Coda, jump to the coda. On the way back, repeats are usually not played again unless the music says so. A slash with two dots filling a bar means play the previous bar again, and simile means keep doing what you’ve been doing.

15. Texture, voices and instruments

Texture is how the layers of a piece fit together. Monophony is one melody alone, like a single voice or a crowd singing in unison. Homophony is a melody over chords that move with it: a hymn, or a song with piano. Polyphony is several independent melodies at once, woven together; the art of writing it is counterpoint, and a round such as Frère Jacques is the simplest example.

Timbre (say TAM-ber) is tone colour: why a flute and a violin playing the same note at the same loudness still sound different. Composers choose instruments for their timbre as a painter chooses colours.

Voices are grouped by range, highest to lowest: soprano, mezzo-soprano, alto (or contralto), tenor, baritone and bass. A choir is often written in four parts, SATB. The orchestra’s instruments fall into four families: strings (violin, viola, cello, double bass), woodwind (flute, oboe, clarinet, bassoon), brass (horn, trumpet, trombone, tuba) and percussion (timpani, drums, cymbals, xylophone).

Some instruments are transposing: their written notes aren’t the pitches you hear. A B♭ clarinet or trumpet playing a written C sounds B♭, a tone lower, and guitar music sounds an octave lower than written. Piano, flute, violin and voice are written at the pitch they sound.

16. Reading piano music

Piano music adds a few signs of its own. The two hands share the grand staff, usually the right hand on the treble staff and the left on the bass, though either hand can cross into the other’s staff; R.H. and L.H. (or m.d. and m.s.) say which hand when it isn’t obvious.

• Finger numbers over or under notes: 1 is the thumb, 2 the pointer, 3 the middle finger, 4 the ring finger and 5 the little finger, on both hands.
• Ped. and a star, or a bracket under the staff: press and lift the sustain (right) pedal, which keeps notes ringing after you let the keys go.
• una corda: the soft (left) pedal; tre corde releases it.
• 8va with a dotted line: play an octave higher than written until the line ends; 8vb, an octave lower; loco, back to normal.
• A wavy line before a chord: roll it, bottom note first.

The best way to make all of this stick is to read real music, a little every day. Our free piano sheet music starts in C position with nothing but the treble and bass clefs, crotchets and minims, and adds one new idea at a time, and every piece has a play button so you can check yourself. Practise the notes on the online piano keyboard, or type any tune into the sheet music player and hear it back.

Part two · Reference

Signs and symbols

Every common sign in written music, drawn on the staff, grouped by what it does. Search for a name, or jump to a group: staff and clefs, notes, rests, sharps and flats, time signatures, dynamics, articulation, ornaments, repeats, tempo, piano, chord symbols.

Charts

Note values

Each note is half the one above it. Beats are counted with a crotchet as one beat, as in 2/4, 3/4 and 4/4.

Tempo markings

From slowest to fastest. The speeds are a rough guide, mostly the bands printed on a traditional metronome; composers and editions vary, and the character of the word matters as much as the number.

Key signatures

All fifteen key signatures, each with its major key and relative minor. Three pairs (B and C♭, F♯ and G♭, C♯ and D♭) are the same sounds written two ways.

Scales and modes

Chord formulas

Every chord on C. The formula counts from the root in steps of the major scale: 3 is the major third, ♭3 the minor third, and so on. To build the same chord on another root, keep the formula and move the notes.

Questions people ask

Written by the friendly AI team at Digital Greenhouse and checked by John. If you spot a mistake, tell us and we’ll fix it. The staff examples are drawn by abcjs; the piano sound is the Salamander Grand Piano V3 by Alexander Holm (CC BY 3.0), trimmed and level-matched by us.