Accidentals

Accidentals indicate a note whose pitch (or pitch class) is not a member of a scale or mode indicated by the most recently applied key signature. An accidental sign raises or lowers the following note from its normal pitch, usually by a semitone. Accidentals predeceasing a measure apply within the entire measure, unless canceled by another accidental sign, or tied into a following measure. In musical notation, the symbols used to mark accidentals are one of the following:

• sharps: ♯

• flats: ♭

• naturals: ♮

(more info: Wikipedia)

Related content:

• Bagpipe scale notated with accidentals