The key signature of a piece of music is the sharps or flats listed after the clef. This is to avoid the repetiton of accidentals in the score. They are listed on every line of music, which signifies what key the composer has chosen.

There is a key signature for each major key (C Major has no sharps or flats). Each major key, in turn, shares its signature with the minor key whose scale begins three semitones lower - in other words, on the 6th note (the submediant) of the major scale.

List of key signatures

Here is a complete list of key signatures:

Key Sig.	Major Key	Minor Key
No sharps or flats	C major	a minor

Key Sig.	Major Key	Minor Key
1 flat	F major	d minor
2 flats	Bb major	g minor
3 flats	Eb major	c minor
4 flats	Ab major	f minor
5 flats	Db major	bb minor
6 flats	Gb major	eb minor
7 flats	Cb major	ab minor

Key Sig.	Major Key	Minor Key
1 sharp	G major	e minor
2 sharps	D major	b minor
3 sharps	A major	f# minor
4 sharps	E major	c# minor
5 sharps	B major	g# minor
6 sharps	F# major	d# minor
7 sharps	C# major	a# minor