An accidental is a note that is not in the currently used scale. It is indicated in standard musical notation by any of several symbols, most frequently the sharp (♯), flat (♭), and natural (♮) symbols. An accidental sign raises or lowers the immediately following note and any repetition of it in the same measure from its normal pitch, usually by a semitone, although there are double sharps and double flats, which raise or lower the indicated note by two semitones. An accidental usually also affects all repetitions of the note within the measure in which it appears as well as the same note in other octaves, unless it is canceled by another accidental sign.