Key Signature was mentioned in passing during my explanation of the Circle of Fifths during my last entry. The Key Signature is a group of sharps or flats located on the staff to signify when a note is sharp or flat through out a piece of music.
In the Key Signature above, which could represent something in either the key of A major or F# minor. Notice the sharps placed in the positions of the C, F, and G. This means that anytime a C, F, or G note is shown after this, it is to be sharp unless altered by an accidental, which are pictured below in the order of a sharp, a flat, and a natural. An accidental is a note outside of the Key Signature.
The Key Signature is most often placed after the Clef, although it may appear elsewhere, such as after a double bar line. You may refer to the Circle of Fifths in the previous post to see what key signature goes with which scales, or you can use mnemonics.
For the sharps: Father Charles Goes Down And Ends Battle. (FCGDAEB)
For the flats: Battle Ends And Down Goes Charles’ Father. (BEADGCF)
Notice that the order of the sharps and flats are inverse of eachother. So knowing one, you know the other.
