Answer:
The three main types of clef signs used in modern music notation are the G-clef, C-clef, and F-clef
Placement on different lines of the staff indicate a different tessituras, with nine possible distinct clefs.
In contemporary music literature, only four clefs are used regularly: the treble clef, the bass clef, the alto clef, and the tenor clef with the treble and bass clefs the most common.