Collection of sharp and flat symbols at the beginning of a musical staff, indicating the tonality of the music written on that staff.

For the non-musical people out there: listen to your average pop song. Usually there's a certain note or set of notes (called a chord) that feels like home -- a good landing place for a note sequence. That "home" note is the base of the tonality or key. This key is represented in musical notation by a set of markings indicating modifications, either raising the note a half-step (sharp) or lowering it one half-step (flat), to any notes written on a particular line or space.

Each key signature represents two possible keys, a major and a minor key. The most simplistic way to explain this is that major keys sound happy, and minor keys sound sad. As with most simplistic explanations, though, that doesn't do justice to the concept. The minor key for a given major key signature starts on the perfect sixth of that major key.

C major is the key requiring no modifications (accidentals), and hence requires no key signature (null key signature?).

In music notation, the key signature is a series of sharps, flats, and/or natural signs at the beginning of a staff following the clef (but before the time signature). It indicates what major key the music is to be played in. If the song is in a minor or diminished key, the key signature may use natural symbols where certain sharp or flat symbols would be for the equivalent major key. Like the clef, but unlike the time signature, the key signature reappears on every staff line.

The sharps or flats in the key signature are to be carried through the entire piece as the "default" for that note. If a key signature lists F sharp and C sharp, for example, then any time an F or C is encountered on the staff it should be interpreted as F sharp or C sharp instead. A key signature can be changed in the middle of a piece, and if so, the new key signature is used at the beginning of each staff after that point.

The sharp or flat symbols in a major key signature are always arranged in a certain order, sometimes known as the circle of fifths. If sharps are used, this order is: F, C, G, D, A, E, B. If flats are used, the order is: B, E, A, D, G, C, F.

A key signature (A major in this case) looks something like this on the staff:

----| /----#-----------------------------------------------
   /|    #                                                 
 |  |  |                                                   
  \ |  |                                               

A rather elegant lame mnemonic for the order of sharps in a key signature is "Father Charles Goes Down And Ends Battle." This has the interesting property that, if you reverse it to get the order of flats, it remains gramatical, to whit: "Battle Ends And Down Goes Charles' Father".

An interesting thing about key signatures is that at the end of the circle of fifths--the sharp keys--and the circle of fourths--the flat keys--the Ends Battle and Charles' Father in Grimace's write up, the sharps and flats are white notes.

This is to be expected, though most piano students do not. It is simple arithmetic: there are seven different notes in the octave, each of which can be sharped or flatted, but only five black ones, hence E# and B# are played as F and C respectively, and Cb and Fb are played as B and E respectively.

Regardless of the colour, all notes shoud be treated the same, though most piano students, including myself, even now, cannot yet do it perfectly.

Learning the names of all the key signatures can be tricky for music theory novices. Here now is your very own key signature Q and A.

Is the key sharp or flat?

This one's easy. If the name of the key has "flat" in it, it's a flat key. Otherwise, it's a sharp key. The only exception to this is the key of F major, which is flat—sorry, you just have to remember that one.

How many sharps in the key of (whatever)?

To find the sharps that are in a sharp key, take the name of the key (e.g., A major) and find the note two half steps down from that (in our example, that would be G). This is the last sharp in the key. If you know the order of sharps (what? You don't? Fine; it's FCGDAEB), then you can easily find the number of sharps in the key (in our example, there are three of them, since G is the last one). Ta-da!

How many flats in the key of whatever?

After the last one, this should be a breeze. The rule: The name of the key is the second-to-last flat in the key. So for Bb major, we move along the order of flats (oh, fine; it's BEADGCF) and find that there are 2 flats in the key of Bb. (Note: Finding out the number of flats in F major is confusing this way; best to just remember that there's only one.)

I'm looking at this music, and I can count how many stupid sharps there are. But what's the name of the key?

All right, now let's do this all backwards. If you're looking at a key signature with a bunch of sharps, and you don't know what the h-e-double-hockey-sticks it's called, remember this: take whatever note the last sharp is on, and go up two semi-tones. So if there are four sharps, and the last one's on D (which it always is–order of sharps, remember?) then the name of the key is E major.

But now I've got a bunch of flats! Help!

Never fear. For any key with flats, just look at the second-to-last flat, and there's the name of the key. So if there are five flats, then the penultimate flat is Db, which is the name of the major key.

But what's with this major and minor business?

For that, I recommend you check out the WUs under relative minor and parallel minorthey've got the goods.

key signature is the set of sharps (#) or flats (b) that is written at the beginning of a piece of music to indicate the key of the piece. These sharps or flats are located in front of a clef, either a bass or a treble clef.

The Order of Flats:

The Order of Sharps:

As you can see, it's just reversed for each. A good way to remember which way is which is that the symbol for a flat (b) looks like a B, and the order begins with a B.

To name a flat key, you count the number of flats, and the next to the last flat names the key. For example, if there are 3 flats on the staff, they are B, E, and A. So it's an E flat.

To name a sharp key, you count the number of sharps, and then take the next alphabetical letter up. For example, if you have 4 sharps, they'd be F, C, G, D. So it would be E.

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