Each symbol applies to all notes in the same pitch class-for example, a flat on the third line of the treble staff (as in the diagram) indicates that all notes appearing as Bs are played as B-flats. This applies through the end of the piece or until another key signature is indicated. In a key signature, a sharp or flat symbol on a line or space of the staff indicates that the note represented by that line or space is to be played a semitone higher (sharp) or lower (flat) than it would otherwise be played. If the piece contains a section in a different key, the new key signature is placed at the beginning of that section. The initial key signature in a piece is placed immediately after the clef at the beginning of the first line. In Western musical notation, a key signature is a set of sharp ( ♯), flat ( ♭), or rarely, natural ( ♮) symbols placed on the staff at the beginning of a section of music. Key signature showing B ♭ and E ♭ (the key of B ♭ major or G minor) Key signature showing F ♯ and C ♯ (the key of D major or B minor) For use in cryptography, see Key signature (cryptography).
