Accidentals are symbols that
indicate the alteration of the pitch of a tone.
A sharp () raises the pitch of a tone by a half step.
A flat () lowers the pitch of a tone by a half
step.
A natural
() is used to cancel a sharp or flat.
A double flat
() lowers the pitch of a tone
by two half steps.
A double sharp() raises the pitch of a tone by two half
steps.
A natural is sometimes used
in conjunction with a sharp or flat in order to cancel one of
the flats/sharps of a double sharp or double flat.
Notice in the musical examples above, the accidentals are always
placed in front (to the left) of the notes they affect. On the other
hand, when writing about music, the word or symbol representing
the accidental follows the letter name (e.g., "A flat"
or "G#").
The black keys of the keyboard can be labeled with either flats
or sharps. Roll your mouse over the keyboard to see the black
keys labeled as sharps.