Before I can explain sharps and flats, I need to explain something called a semitone (to our US visitors a half step).
Semitones
A semitone is defined as the closest distance between two sounds played on a piano.
So if you play any key on a piano and go to it's nearest neighbour you have travelled
one semitone or a half step. Normally this would take you from a white key to a
black key or visa versa, but there are two places where the white keys do not
have a black one between them (E-F and B-C), so these two pairs of notes are
only a semitone apart.
Sharps #
A sharp (#) is a sign which is written in front of a note and raises the pitch of that note by one
semitone. In the example shown, the note G is followed by the note G sharp.
Flats b
A flat (b) is a sign which lowers the pitch of a note by one semitone. Below we see
the note B being lowered to B flat.
