Sharps (#) and Flats (b)
Although there are only seven letter names used in music, there are actually twelve different notes used in music. The extra notes are created by sharps and flats.
A sharp (indicated by the symbol #) raises the pitch of a note by a semitone. E.g. the note C sharp (C#) is higher than C and falls halfway between the notes C and D. A flat (indicated by the symbol b) lowers the pitch of a note by a semitone. E.g. the note Db is lower than D and falls halfway between D and C. This means that the notes C# and Db are exactly the same.
This is easy to understand if you look at the following piano keyboard diagram. The white notes are all the natural notes (A B C D E F G) and the black notes are the sharps and flats. D# is the same as Eb, F# is the same as Gb, etc. Sometimes one is used and sometimes the other, depending on the musical situation and the key the music is written in. Keys are discussed in the next lesson.
The Natural Sign
This is a natural sign.
A natural sign cancels the effect of a sharp or flat for the rest of that bar, or until another sharp or flat sign occurs within that bar.
With the inclusion of sharps and flats, there are 12 different notes within one octave:
Note that there are no sharps or flats between B and C, or E and F because those notes are already a semitone apart. You can see this clearly on the piano keyboard, as the notes B and C, and E and F have no black notes (sharps/flats) between them.
