What is a clef?

Since we can only use 5 lines at a time, but we have up to 88 notes we might want to play, we need a way of “covering more ground.”  We do that by using a clef.  A clef is a symbol placed at the beginning (left) of a staff — to tell us what kind of staff it is.  For piano music, the simple distinction of “high” and “low” notes is enough to get started . . . so we have a clef for “high” notes, called a treble clef . . .