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Lesson 26 Intermediate Chapter III — Intermediate Skills

Guitar Music Keys & Key Signatures Explained

Understanding keys is the single biggest leap in music theory for guitarists. Once you know how keys work, chord progressions make sense, song structures become predictable, and moving between songs in different keys becomes straightforward.

What is a Key?

A key is a set of seven notes that sound naturally harmonious together. Music written in a particular key uses primarily those seven notes — and the chords built from them — creating a sense of belonging around a central note called the tonic.

Until now all the music in this course has been in the key of C (no sharps or flats). But most music is written in other keys — and those keys introduce sharps and flats that apply to the whole piece.

Key Signatures

Rather than writing a sharp or flat sign before every affected note throughout a piece, composers write all the required sharps or flats at the beginning of each line of music, right after the treble clef. This group of signs is called the key signature.

Once you see a key signature, those sharps or flats apply to every note of that letter name throughout the entire piece — unless a natural sign cancels them temporarily within a bar.

✦ Read the Key Signature First

Before playing any piece of music, look at the key signature. Count how many sharps or flats are shown. This tells you which key the music is in and which notes need to be sharpened or flattened throughout.

Sharp Keys

Sharp keys add one sharp at a time, in a fixed order:

Key of G — 1 Sharp

Sharpen every F → F#
Relative minor: E minor

Key of D — 2 Sharps

Sharpen F# and C#
Relative minor: B minor

Key of A — 3 Sharps

Sharpen F#, C#, G#
Relative minor: F# minor

Key of E — 4 Sharps

Sharpen F#, C#, G#, D#
Relative minor: C# minor

Flat Keys

Flat keys also add one flat at a time, in their own fixed order:

Key of F — 1 Flat

Flatten every B → Bb
Relative minor: D minor

Key of Bb — 2 Flats

Flatten Bb and Eb
Relative minor: G minor

Key of Eb — 3 Flats

Flatten Bb, Eb, Ab
Relative minor: C minor

Key of Ab — 4 Flats

Flatten Bb, Eb, Ab, Db
Relative minor: F minor

Chords That Belong Together in Each Key

Every key has its own set of naturally occurring chords. Knowing these helps you predict what chords will appear in any song:

You do not need to memorise all of these immediately — but understanding that chords come in families that belong to a key makes song structure much more logical.

⚠ Scales on Guitar

Each key is built from a scale — a specific sequence of notes. The scale of G major plays the notes G A B C D E F# in order. Try playing this on the 3rd string in first position: G (open), A (2nd fret), B (4th fret), then moving to the 2nd string: C (1st fret), D (3rd fret), and so on. Hearing the scale helps you feel the key.

What's Next?

Lesson 27 takes fingerpicking to the next level with advanced patterns — clawhammer technique, Travis picking, and melody fingerpicking for folk and country styles.

Questions & Answers

Frequently Asked Questions

Common questions about guitar music keys & key signatures explained

A key is a set of seven notes that sound harmonious together, built from a specific starting note called the root or tonic. Music written in the key of G uses primarily the notes G A B C D E F# — and the chords built from those notes. The key determines the overall tonal centre and emotional character of the music.

A key signature is the group of sharp or flat signs written at the beginning of every line of music, immediately after the treble clef. It tells you which notes to sharpen or flatten throughout the entire piece — so those signs do not need to be repeated before every single affected note.

The key of G major has one sharp: F#. Every F in music written in the key of G is played as F# unless a natural sign cancels it. The key of D has two sharps (F# and C#), A major has three, E major has four, and so on. Each new sharp key adds one more sharp.

The naturally occurring chords in the key of G are: G major, A minor, B minor, C major, D major, E minor, and F# diminished. In practice, the most commonly used are G, Am, C, D, and Em — which appear together in hundreds of folk and pop songs.

Sharps and flats allow music to be played in any of the 12 possible keys, not just C major. Different keys suit different voices, instruments, and emotional characters. Guitarists often choose a key based on which open chords are available, or use a capo to change the key while keeping the same chord shapes.

Every major key has a relative minor key that uses exactly the same notes. A minor is the relative minor of C major — same notes (no sharps or flats) but with A as the tonal centre rather than C. Minor keys generally have a darker, more melancholy quality. E minor is the relative minor of G major.