1) Note-clarifying symbol 2) Staff opening 
(from the article `clef`) Music for instruments and voices is written in the clef corresponding most closely to the range of their parts. The treble, or G, clef fixes the ...
This clef tells the musician where the first G above Middle C is (the second line, where the curl wraps around). Because it shows where G is (and it kind of looks like one), a treble clef can also be called a G clef.
[n] - a clef that puts the G above middle C on the second line of a staff
symbol placed on the five-line staff in traditional notation indicating the pitch of the notes and locating G on the second line from the bottom.
treble staff noun a clef that puts the G above middle C on the second line of a staff