Music Theory Basics: Notes, Scales, Chords and Rhythm Made Simple

Music theory is simply a way of naming what we hear. You do not need it to enjoy music, but knowing the basics makes it much easier to learn an instrument, write songs and understand why some music sounds happy, sad or relaxing. This guide covers the essentials in plain language.

Notes and the musical alphabet

Western music uses seven letter names: A B C D E F G. After G, the letters start again at A, one octave higher. Notes an octave apart sound like the same note, higher or lower; physically, the higher one vibrates exactly twice as fast.

Between most of these letters there are extra notes, the black keys on a piano. Altogether there are 12 different notes in an octave:

C – C♯/D♭ – D – D♯/E♭ – E – F – F♯/G♭ – G – G♯/A♭ – A – A♯/B♭ – B

A sharp (♯) raises a note by one step; a flat (♭) lowers it. C♯ and D♭ are the same key on the piano. Notice there is no black key between E and F or between B and C.

Half steps and whole steps

The distance between two neighbouring notes (for example E to F, or C to C♯) is a half step (semitone). Two half steps make a whole step (tone), like C to D. These two distances are the building blocks of scales.

The major scale

A scale is a set of notes in order. The major scale sounds bright and happy, and it follows this pattern of steps:

Whole – Whole – Half – Whole – Whole – Whole – Half

Starting on C, this gives C D E F G A B C: all the white keys. Start the same pattern on G and you need one sharp: G A B C D E F♯ G.

The minor scale

The natural minor scale sounds darker or more emotional. Its pattern is:

Whole – Half – Whole – Whole – Half – Whole – Whole

A minor uses the same notes as C major (A B C D E F G A). Keys that share notes like this are called relative major and minor.

Keys

The key of a song is its home note and scale. A song "in G major" uses mostly the notes of the G major scale and feels resolved when it returns to G. The key signature at the start of sheet music shows which sharps or flats the key uses.

The circle of fifths arranges the 12 keys so that each one is a fifth above the last (C, G, D, A, E, B, F♯…). Neighbouring keys share all but one note, which is why songs often move between them.

Intervals

An interval is the distance between two notes. Some common ones:

Chords

A chord is three or more notes played together. The simplest is a triad, built by stacking thirds:

• Major triad: root + major 3rd + perfect 5th (C–E–G). Bright.
• Minor triad: root + minor 3rd + perfect 5th (A–C–E). Darker.
• Diminished triad: root + minor 3rd + diminished 5th (B–D–F). Tense.

Add another third and you get a seventh chord, such as Cmaj7 (C–E–G–B) or Am7 (A–C–E–G). Seventh chords give jazz, bossa nova and lo-fi their soft, sophisticated sound. You can see and hear any chord in our chord finder.

Chords in a key

Building a triad on each note of the C major scale gives seven chords. Musicians number them with Roman numerals (capital = major, lower case = minor):

I (C) – ii (Dm) – iii (Em) – IV (F) – V (G) – vi (Am) – vii° (Bdim)

This is the secret behind most songs: they mix these chords in different orders. Our chord progressions guide shows the most common combinations.

Rhythm, meter and tempo

• Beat: the steady pulse you tap your foot to.
• Meter / time signature: how beats are grouped. 4/4 (four beats per bar) is the most common; 3/4 is a waltz; 6/8 has a gentle rocking feel.
• Note values: a whole note lasts four beats in 4/4, a half note two, a quarter note one, an eighth note half a beat.
• Tempo: the speed, measured in BPM (beats per minute). Relaxing music is often 60–80 BPM; lo-fi hip hop around 70–90; dance music 120–130.

Practise keeping steady time with our free online metronome.

Where to go next

1. Learn the C major scale and its seven chords on piano or guitar.
2. Play the progression C – G – Am – F along with a metronome.
3. Try writing a short melody over it, then read how to write a song.