In modern
musical notation and
tuning, an
enharmonic equivalent is a
note,
interval, or
key signature that is
equivalent to some other note, interval, or key signature but "spelled", or named differently. Thus, the
enharmonic spelling of a written note, interval, or chord is an alternative way to write that note, interval, or chord. For example, in twelve-tone
equal temperament (the currently predominant system of
musical tuning in Western music), the notes C and D are
enharmonic (or
enharmonically equivalent) notes. Namely, they are the same key on a
keyboard, and thus they are identical in pitch, although they have different names and different
roles in harmony and chord progressions.