D Sharp as an Enharmonic Note

D sharp and E flat name the same key on a modern equal-tempered instrument, another instance of the enharmonic equivalence that runs through all five chromatic notes in this atlas. Written music chooses between the two names according to the surrounding key signature and harmonic function rather than any difference in the sound produced, since equal temperament by design divides the octave into twelve exactly equal semitones with no acoustic distinction between a pitch's two possible spellings.

D sharp minor and E flat major are, despite naming what modern tuning treats as the identical set of pitches, conventionally written using different key signatures and are associated with different repertoire in practice, since composers and performers generally choose the spelling that produces the simpler, more legible notation for a given passage rather than switching between equivalent spellings freely.