Key Signatures

Key signatures, like time signatures, are important in music because they indicate a certain rule for the notes following the signature. The key signature indicates the key in which the following notes are played in. Like the time signature, the key signature is effective until another key signature is introduced. The key signature is placed between the time signature and the clef at the beginning of the staff.
What is the key? Well as shown the scales described above, each scale has its corresponding sharps and flats. Each set of sharps and flats that correspond to a scale is a key. What this means is that a piece in the key of C major will have no flats or sharps because the C major scale has no flats or sharps.

Major Key Signatures

These key signatures are merely those which are in a major key.

Key Signature	Major Key	Key Signature	Major Key
	C Major
	G Major		F Major
	D Major		B-flat Major
	A Major		E-flat Major
	E Major		A-flat Major
	B Major		D-flat Major
	F-sharp Major		G-flat Major
	C-sharp Major		C-flat Major

Minor Key Signatures

These key signatures may have the same sharps and flats as some major key, but the tonic is different and thus the piece of music ends up sounding very different.

Key Signature	Minor Key	Key Signature	Minor Key
	A Minor
	E minor		D Minor
	B Minor		G Minor
	F-sharp Minor		C Minor
	C-sharp Minor		F Minor
	G-sharp Minor		B-flat Minor
	D-sharp minor		E-flat Minor
	A-sharp Minor		A-flat Minor

Key signatures that look the same but are different because one is major and the other is minor are called relative keys. Thus, the relative minor of C major is A minor. G major is the relative major of E minor.

Key signatures that have the same tonic but are different (have different sharps and flats) are called parallel keys. A major and A minor are parallel keys. E minor is the parallel minor of E major and D major is the parallel major of D minor.

Order of Sharps and Flats

In the key signature, you must write the sharps and flats in a certain order. Sharps follow the pattern of F, C, G, D, A, E, and B (Father Charles Goes Down And Ends Battle). Flats follow the opposite pattern; B, E, A, D, G, C, and F (Battle Ends and Down Goes Charles’s Father). You may also use the circle of fifths. Sharps and flats are never mixed in the key signature.

Remembering Key Signatures

There are tricks for remembering what key signature corresponds to what key. First of all, C major and its relative minor, A minor, have no flats or sharps. For major sharp keys, the name of the key is one semitone higher than the last sharp in the key signature.

For major flat keys, the name of the key is the name of the next to last flat. You must remember that the key of F major has only a Bb.

You can find minor keys if you are given the major keys. You count back from the major key’s tonic three minor scale notes (3 semitones).

There are thirty key signatures total – fifteen major, fifteen minor. A music theory student should strive to memorize every one of these keys because they are extremely important in other subtopics of music theory.