Each note is given a name, a letter from A
to G. Because there are more than seven notes the letters are
repeated in sequence for each new note.
The vertical position on the stave shows the musician
which note to play, as shown in the diagram below.
In order to show the semitone steps
between notes, sharp and flat signs are used. A sharp sign next
to a note means it should be played one semitone higher. A flat
sign next to a note means it should be played one semitone lower.
For example, the note C with a sharp
sign before it would be called C sharp and on a piano the black
key just to the right of it would be played instead of the C key.
The same sharp and flat key on the
piano is used for notes that are next to each other, C sharp and
D flat are in fact the same note but are written differently on
the stave. The composer could use either note and the music would
sound the same.
Notes B and C, and notes E and F are
a semitone apart so do not have 'sharps' and 'flats' between them.