Clef

A clef (from archaic French clef 'key', also spelt clé) is a musical symbol used to indicate the pitch of written notes. Placed on a stave, it indicates the name and pitch of the notes on one of the lines. This line serves as a reference point by which the names of the notes on any other line or space of the stave may be determined. There are three forms of clef used in modern music notation: F, C, and G. Each form assigns its reference note to a line (and in rare cases, a space) depending on its placement on the stave.