Explore Accidentals & Key Signatures with music dictionary guides to sharps, flats, naturals, keys, and tonal notation.
A key signature is a set of sharps or flats placed at the beginning of a staff to indicate the scale on which a piece is based. It defines which notes are to be played consistently sharp or flat throughout a composition unless cancelled by accidentals.
An accidental is a symbol placed before a note to raise or lower its pitch by a semitone or whole tone, temporarily altering the key signature. Sharps, flats, naturals, double sharps, and double flats are the most common accidentals used in Western staff notation.
A double sharp (𝄪) is an accidental that raises a written note by two semitones, equivalent to a whole‑step increase, and is used in highly chromatic music and certain key signatures.
The sharp symbol (♯) is an accidental that raises the pitch of a note by one semitone. It appears to the left of a notehead or at the beginning of a key signature, indicating that the affected pitch is to be played a half step higher than written.
The flat (♭) is a musical accidental that lowers a pitch by one semitone. It appears to the left of a note or in key signatures and is essential for indicating pitch alterations in Western notation.
A double flat (𝄫) is an accidental that lowers a note’s pitch by two semitones, used in highly chromatic music and complex key signatures.
The natural symbol (♮) is a musical accidental that cancels previous sharps or flats, restoring the pitch to its original diatonic state within the measure.