Music theory for beginners

Music theory is not a set of rules you must obey. It is a description of what musicians have found works, and a vocabulary for talking about it. Nobody is going to stop you breaking any of it.

This page covers the ideas that everything else depends on. It should take about fifteen minutes.

1. There are only twelve notes

Western music divides the octave into twelve equal steps called semitones. On a piano, twelve consecutive keys — black and white — take you from one note to the same note an octave higher.

Seven of them get letter names, A through G. The other five are named with sharps and flats relative to their neighbours.

The pattern repeats every octave. Learn it once and you know it everywhere.

2. Written music encodes pitch and duration

Notation does two jobs at once.

Pitch is shown by vertical position on a five-line staff, decoded by the clef at the start.

Duration is shown by the note's shape — hollow, filled, flagged, beamed. See note values.

Once you see notation as two overlaid systems rather than one dense one, it becomes much less intimidating.

3. Distance is what matters, not absolute pitch

Music is built from relationships. The distance between two notes is an interval, and intervals are the real unit of music theory.

Twinkle Twinkle starts with a jump of a perfect fifth. That is true whether you start on C, on F♯ or on anything else. The tune is the pattern of distances — which is why you can transpose a song and it stays the same song.

Everything in the following sections is defined in intervals.

4. A scale is a pattern of steps

A scale is a set of notes in order, built from a fixed pattern of tones and semitones.

The major scale pattern:

tone – tone – semitone – tone – tone – tone – semitone

Apply it starting on C and you get the white keys. Apply it starting anywhere else and you need sharps or flats to keep the pattern — which is where key signatures come from.

Change the pattern and you get a different flavour. The minor scale has a flattened third, sixth and seventh, and that is essentially the whole difference.

5. A key is a home base

A key is the scale a piece draws on, plus the note it treats as home.

A piece in C major uses the notes of the C major scale and keeps returning to C. That returning is what makes an ending sound like an ending.

The key signature at the start of the staff tells you which sharps or flats apply throughout, so they do not have to be written on every note.

6. A chord is notes stacked in thirds

Take a note, add the note two letters up, then two more.

C, E, G — that is a C major chord.

Lower the middle note by one semitone — E becomes E♭ — and it is C minor. That single semitone is the whole difference between the two chord qualities. See major vs minor chords.

Build a chord on each note of a major scale and you get the seven chords that sound at home in that key. That is why so many songs use the same handful of chord relationships in different keys.

What to do next

Pick one thing and get it solid before adding another. In order:

1. Treble clef notes — read pitch
2. Note values — read rhythm
3. What is an interval — the hinge concept
4. The major scale — the reference for everything else

Then read how to learn music theory for a longer-term plan.