What a Key Signature Tells You
Instead of writing a sharp or flat sign next to every affected note, a key signature places them at the start of each staff. Every note with that letter name is played sharp or flat throughout — unless a natural sign (♮) cancels it for a specific note.
The key signature also tells you which major (or minor) key the piece is in, which helps you understand the scale, the chords, and where the music will feel "at home."
Sharp Keys
Sharps are added in the order: F C G D A E B.
| Sharps | Major Key | Relative Minor |
|---|---|---|
| 0 | C major | A minor |
| 1 — F♯ | G major | E minor |
| 2 — + C♯ | D major | B minor |
| 3 — + G♯ | A major | F♯ minor |
| 4 — + D♯ | E major | C♯ minor |
Flat Keys
Flats are added in the order: B E A D G C F — the reverse of sharps.
| Flats | Major Key | Relative Minor |
|---|---|---|
| 1 — B♭ | F major | D minor |
| 2 — + E♭ | B♭ major | G minor |
| 3 — + A♭ | E♭ major | C minor |
| 4 — + D♭ | A♭ major | F minor |
Major and Minor Keys
Every major key has a relative minor that uses the same notes and the same key signature, but starts three semitones lower. C major and A minor both have no sharps or flats — but A minor feels darker and more unsettled.
You can also have a parallel minor — the same tonic but a different key signature. C major and C minor share the same starting note but C minor has three flats.