Accidentals

Sometimes a tune departs momentarily from the key, necessitating the cancelling of what is required by the key signature. This is done by putting the required sign—sharp, flat, or natural—beside the note in question.

A natural sign ( ) means “not sharp or flat,” so when we refer to A-natural we simply mean plain A, not altered by a sharp or flat.

Accidentals affect all notes until the end of the measure, after which the change is cancelled. The only exception is when a note is tied over, in which case it retains its changed status. The examples below make these rules clear.