A key signature indicates which notes a musician should raise or lower while playing a piece of music, and is denoted with sharp (♯) or flat (♭).
The key signature is typically marked at the beginning of the music, and is generally applicable throughout the entire piece or movement. There may be instances of key changes within the music, in which case a new key signature will be used.
The key signature helps the musician understand the musical structure of the piece. For example, if the key signature is written by 2 sharps, the key will be D Major (or B minor).
Writer: Frankie Chan